The computer's domain name can be abcd. Computer Domain Name - What is it? Why is it necessary? How to recognize him? Example input and output data

In order for information to be accurately transmitted from one computer to another, it is necessary to have unique addresses that can be used to uniquely determine (identify) the recipient of the information. Just as regular mail delivers postal items to addresses that include a region, city, street, house, apartment, so on the Internet, information packages are delivered to addresses, only the address indicates not houses and streets, but network numbers to to which the recipient computer is connected and the numbers of the computers themselves in these networks.

So, each computer connected to the Internet has its own unique IP address.

IP address is a unique number that uniquely identifies a computer on the Internet. An IP address is four numbers (octets) separated by dots, for example, 194.67.67.97 (there is no dot after the last number).

This address is deciphered from left to right. The first number is the number of the largest network within the Internet, the last is the number of a specific computer. The second and third numbers indicate sections of the network, for example, regional and local networks.

Each number can be in the range from 0 to 255, which corresponds to an information volume of 1 byte or 8 bits. Thus, an IP address is 4 bytes or 32 bits. If using one byte you can transmit 28=256 options, then using 4 bytes you can transmit 2324 billion options, then a maximum of 4 billion users can be connected to the Internet. Since there is currently a rapid growth in Internet users, and in addition, modern technical advances make it possible to connect not only computers, but also cell phones, televisions, and even refrigerators to the Internet, this address space is becoming very crowded. To expand it, it is planned to transfer the Internet to a 128-bit IP address (maximum users 2128).

What is a domain name?

Each computer, when connected to the global Internet, is assigned its own unique number, called IP ADRESS.

Each web resource also has its own IP Address. The official website of the Yandex company has an IP Address of 213.180.204.11. This number is difficult to remember, but if you write it in the address bar, the browser will open the Yandex company website. The domain name of this website is www.yandex.ru corresponding to the IP address 213.180.204.11.

Having a domain name, instead of a numeric equivalent, makes it possible to access a computer by a name that identifies the owner of the IP address. A domain name serves as a unique name on the Internet and is a simpler and, naturally, more beautiful option for recording this address.

Domain name(English domain name) - a unique identifier that is assigned to a specific IP address (there cannot be two identical ones).

Domain Names maintained and centrally administered by a set of DNS domain name servers. DNS (Domain Name Service) - domain name service. Along with digital addresses, DNS allows you to use your own computer names, so-called Domain Names.

All Domain Name information is stored in a central DNS database, which consists of several powerful computers scattered around the world. This database stores information about the registration date, the physical or legal owner of the Domain Name, as well as the path to the so-called name server - NAMESERVER, which contains the information to which the Domain Name points.

The single Internet directory that defines the basis of DNS is located in the state organization SRI International - Menlo Park, CA, US (Menlo Park, California, USA).

Domain name is the letter address of the computer.

Domain Name or computer letter address can be:

Domain name of the first (top) level - first domain level;

Second level domain name - second level domain;

Third level domain name - third level domain. First level Domain Names are divided into:

	Organizational top level domain names in the USA:		Geographic first level domain names:
arpa	- Old style Arpanet	af	- Afghanistan (Afghanistan)
biz	- businesses firms (commercial)	ca	- Canada
com	- commercial (commercial)	cc	- Cocos Islands
edu	- US educational (education)	de	- Germany (Germany)
gov	- US government	fr	- France (France)
int	- international (international)	ru	- Russia (Russia)
info	- information services	se	- Sweden (Sweden)
mil	- US military (US military)	tv	- Tuvalu (Tuvalu)
nato	- NATO field (NATO)	uk	- United Kingdom (Great Britain)
org	- non-profit organization	zw	- Zimbabwe (Zimbabwe)
net	- network (network services)	ws	- Western Samoa (Western Samoa)

The website www.nic.ru presents all first-level Geographic Domain Names.

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In computer networks, a hub performs the function

switching several communication channels into one by frequency division

concentrations of several bytes in one packet

signal compression

modulation and demodulation of information signals

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Among the listed firewall programs is

Outpost Firewall

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The figure shows a program window like

mail program

firewall

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Data transfer in information systems occurs using certain agreements called

protocols

services

standards

configurations

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Wireless options are

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A named area of ​​external memory of arbitrary length with a certain amount of information is called

sector

cluster

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The system recognizes the file type by its

expansion

location

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Files have the following attributes, which can be reset and set by the user

archival

systemic

only reading

open

accessible

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ASCII word Informatics will take

176 bytes

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Teraflops measure the performance of modern

supercomputer

mainframe computers

small computers

microcomputer

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The principles of operation of a computer system formulated by J. von Neman do not include

homogeneity of memory

program control

targeting

separating program and data memory

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The main characteristic of the processor is

clock frequency

number of expansion slots

response time

access time

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Checks the composition and performance of the computer system

utility software

basic software

system software

application software

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The functions of operating systems are

ensuring dialogue with the user

development of computer programs

file structure maintenance

computer resource management

computer health check

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When copying the formula from cell D2 to cell D4 the formula was obtained

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Based on the values ​​of the range of cells A1:A4, the following diagram was built

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A logical chain has been built Animals ® Mammals ® Felines ® Panther. In object-oriented programming, this sequence can be described by the principle

inheritance

data abstractions

polymorphism

encapsulation

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The ability to use network resources and provide your own computer resources for use by network clients provides

LAN card

network operating system

Post service

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A network where a computer can play the role of both a server and a workstation is called

peer-to-peer

multi-rank

server

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You can protect your personal email account from unauthorized access.

electronic signature

turning off the computer

hiding personal password

enabling login saving mode

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The best domestic computer of the 2nd generation is considered

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The basic configuration of a personal computer includes

keyboard

system unit

sound speakers

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USB flash drives (flash cards) use

electronic non-volatile rewritable memory

magnetic card

small rectangular DVD R/W

magnetic core memory

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Coordinate input devices include

joystick

streamer

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Match standard Windows OS applications with their purpose

Conductor

The address book

creating and editing text documents

displaying files and folders on your computer

personal contact management

creating, viewing and editing raster graphics

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A section of the file system in Windows OS that contains the names of files and folders and information about their location on the storage medium is

FAT or NTFS table

folder tree

The configuration file

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A fragment of a spreadsheet is given. The formula =IF(A2+B2) is entered in cell C3<12;0;МАКС(A2:D2)). При сравнении значений в ячейках C3 и B5 можно сделать вывод, что

the value in cell C5 is equal to the value in cell B5

comparison is unacceptable, because the data received is of different types

the value in cell C3 is greater than the value in cell B5

the value in cell C5 is less than the value in cell B5

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A fragment of a spreadsheet is given. The number of records that satisfy the autofilter condition is

0, because there is no continent named *America in the table

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The table structure of a relational database (DB) will change if

add one or more entries

add or remove a field

change entry name

delete all entries

change field name

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The term “database security” means

immediate and automatic printing of changed data

immediate and automatic launch of antivirus programs

immediate and automatic saving of changed data

immediate and automatic archiving of changed data

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To visualize the formal model of the computational algorithm, we use

verbal form

algorithm diagram

program

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The statement "A language processor that parses the source program line by line and simultaneously performs prescribed actions, rather than generating a compiled program in machine language that is subsequently executed" is true for

translator

compiler

interpreter

parser

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The determinism of an algorithm is the property that

with correctly specified initial data, the algorithm should complete its work in a finite number of steps

the algorithm must be applicable to different sets of source data

the algorithm must end with certain results

the algorithm produces the same result (answer) for the same initial data

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Determine at what values ​​of the variables x, y, z the selected block will be executed 2 times

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In object-oriented programming, the concept of an object corresponds to a schema

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The main types of computers connected to the network are

work station

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The computer's domain name can be

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The correspondence between addresses and types of addresses on the Internet is as follows:

http://abcd.eqwert.com/index.html

E-mail address

unified locator (address) of a resource on the Internet

Computer IP address

Computer domain name

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Resuming a file from the Internet after a connection failure is provided by the service

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A malicious program that gets onto a computer under the guise of being harmless and cannot reproduce itself is

invisible

Trojan horse

computer virus

network worm

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The first commercially sold laptop was released in

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Expansion slots can accommodate

sound adapters

video cards

printers

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Initial testing and computer boot programs are stored

in RAM (random access memory)

on external memory devices

in ROM (read only memory)

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The Print dialog box does not contain a control such as

command buttons

entry field

slider field

combo box

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Moving from one folder to another, the user sequentially visited the DOC, USER, SCHOOL, D:\, LETTER, INBOX folders. With each move, the user either moved down to a lower level of the folder, or moved up to a higher level. Specify the full name of the folder from which the user started moving

D:\LETTER\INBOX

D:\DOC\USER\SCHOOL

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The mask for the file name is given: k*t.d*. The file name does not match the specified pattern

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The table structure of a relational database is completely defined

a list of field names indicating their types and other additional properties of the data contained in them

setting key fields

list of record names

number of records in the database

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The world's first computer was called

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In von Neumann computer architecture, the part of the processor that executes instructions is called

control device (CU)

input device

Arithmetic Logic Unit (ALU)

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Entering, editing and formatting text data allows you to

utility (service) software

tool software

system software

applied BY

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The set of operating system tools that ensure the interaction of devices and programs within a computer system is

GUI

hardware-software interface

user interface

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A fragment of a spreadsheet is given. The formula from cell A4 is copied to B4:C4. Based on the data from block A4:C4, a radar chart was constructed. In A4, instead of "?" function is used

MAX

AVERAGE

SUM

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A table obtained from a collection of related tables by selecting rows that satisfy specified conditions on field values ​​is

data schema

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When solving a problem on a computer, the “Programming” stage includes

program improvement

choosing a programming language

development of a mathematical model

determination of the form for issuing results

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Writing the expression y = Ax2+ Bx + C in algorithmic language (we denote exponentiation by ^) has the form

y = A*x^2 + B*x + C

y = (A*x)^2 + B*x + C

y = Ax^2 + Bx + C

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A block diagram of the algorithm is given. If the initial values ​​of variables A, B and C are 3, 3 and 1 respectively, then the value of variable F will be equal to

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A network topology where several computers are connected into a network by a switch is called

peer-to-peer

ring

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There is a message with a volume of 223 bits. In megabytes, the size of this message is

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One of the functions of the system software is

file system organization

checking the disk for errors

Disk Defragmenter

data archiving

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During the study of traffic flow along city highways, dependences of the speed of vehicles on the number of vehicles on the highway for different times of the day were obtained, presented in the form of a series of formulas. The conditions for applying certain formulas in different situations are determined, and the algorithm is written in the selected programming language. All described actions represent stages of solving the problem of studying traffic flow. The next stage, according to technology, should be

Testing and Debugging

Program support

Programming

Algorithm development

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In the given fragment of the block diagram,

comparison of variables A, IN, WITH

exchange of variable values A And WITH

exchange of variable values IN And WITH

exchange of variable values A And IN

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A program was developed using object-oriented programming tools. To calculate the sum of two numbers, a sum function has been created, which uses the value of the corresponding properties of the objects “Input field 1” and “Input field 2” as input arguments. This function is executed when processing the “One click of the Amount button” event. The resulting amount changes the object “Input field 3”

base class

property

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The generalized geometric characteristic of a computer network is called

network operating system

logical network architecture

network card

network topology

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The main characteristics of the processor are

clock frequency

bit depth

response time

amount of built-in cache memory

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The concept of "variable" in traditional programming languages ​​is defined as

any complete minimal semantic expression in a programming language

a named area of ​​memory in which a value is stored

function word in a programming language

description of the actions that the program should perform

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The book has 500 pages. Each page of the book has 20 lines of 64 characters. In ASCII encoding, the volume of the book will be equal to

a computer user can enter 100 characters per minute, the power of the alphabet used in the computer is 256. how much information is in bytes

can be entered by the user into the computer in 1 minute

1. A personal computer is used for:

A. Collection of information
b. Information processing
V. Entering information
d. Information storage

2. A personal computer consists of blocks:
A. Mouse
b. Keyboard
V. Hardware unit
Xerox

3. The keyboard is used for:
A. Typing
b. As a palm rest
V. Entering commands
d. Inputting disks

4. The system unit contains:
a.Hard drive
b.Memory
V. Keyboard
d. Processor

6. The hard drive can be of the following sizes:
A. 1.44 MB
b. 1 GB
V. 40 GB
800 MB

7. Printers are:
A. Laser
b. Photocopying
V. Drip-jet
d. copying

8. The modem is used for:
A. Internet access
b. To transmit information over a telephone line
V. for games via local network
g. to convert sounds

9. Multimedia is a combination of:
A. Sound
b. Printer
V. Video
Kolonok

10. Disks are:
a) Magnetic
b) hard
c) soft
d) liquid

11. A computer is...
A. Electronic device with keyboard and screen.
b. A device for performing calculations.
V. A universal device for storing, processing and transmitting information.
d. Gaming device

12. The minimum basic set of computer devices includes...
A. Monitor, keyboard, system unit.
b. Disk drive, printer, monitor.
V. Monitor, printer, keyboard.
g. monitor, scanner, keyboard.

13. Specify in which device group the input/output devices are listed
A. Streamer, hard drive, mouse.
b. Monitor, printer, keyboard.
V. Winchester, laser disk, floppy disk.
floppy disk, mouse, printer

14. Specify in which device group the input devices are listed
A. Printer, hard drive, mouse.
b. Mouse, keyboard, joystick, light pen, scanner.
V. Monitor, printer, plotter, speakers.
g. scanner, monitor, plotter.

15. Indicate which of the listed groups of devices belongs to the external memory of the computer?
A. Monitor, floppy disk, mouse.
b. Floppy drive, floppy disk, RAM.
c. Magnetic tape, laser disk, floppy disk.
g. disk, monitor, hard drive.

16. What output device can be used to obtain a paper copy of a document?
A. Monitor.
b. A printer.
V. Scanner.
g. keyboard.

17. Where is information stored (does not disappear) after the computer is turned off?
A. In RAM.
b. In permanent memory.
V. In the processor.
d. In the monitor.

18. Where is the hard drive usually located?
A. On the monitor.
b. In the system unit.
V. In the drive.
d. In the printer.

19. What device is designed to convert and transfer information between remote computers?
A. CPU.
b. Drive.
V. Modem.
g. monitor

20. Video memory is a part of RAM that is intended for...
A. Storing text information.
b. Storing information about the graphic image on the screen.
V. Permanent storage of graphic information.
g.Sound storage.

You need to write a program... Assignment: The address requested by the user usually consists of four parts, of which the first three

are domain names of different levels and are separated by dots, and the last one is separated from them by a colon and is the port that the user accesses. For example, when a user accesses www.ifmo.ru:8080 word ru is a first level domain name, the word ifmo- second level domain name, word www- a third-level domain name, and 8080 is a port.

You need to list all the different ports that users accessed from a list of user requests in this format.

Input File Format

In the first line of the input file input.txt there is one natural number n (1 ≤ n ≤ 100) - the number of addresses in the list given to you. In the following n The lines contain the addresses themselves in the format described above.

All domain names at all levels consist only of lowercase letters of the Latin alphabet, and ports - only numbers. The length of any address given to you does not exceed 250 characters.

Output file format

In the first line of the output file output.txt print one integer k- the number of different ports accessed by users. In the following k lines output the ports themselves. Each port must be printed exactly once on a separate line. Ports can be displayed in any order.

Example input and output data

input.txt

3
www.ifmo.pl:3389
www.ya.pl:65535
www.ifmo.kz:3389

output.txt

2
65535
3389

Answer all questions urgently; incomplete answers will be deleted as spam) thank you 1. What is Cache memory?

a) memory in which the program is being processed at a given time;
b) memory in which information is stored after the computer is turned off;
c) ultra-random access memory for storing frequently used data in RAM;
d) memory in which system files of the operating system are stored 2. Is the capacity of the central processor determined? a) the width of the control bus b) the name of the processor (80 286.80 386.8 486) c) the width of a binary number that can be processed in one clock cycle of the processor d) the clock frequency of the processor 3. PC system software is divided into types? a) user programs and training programs b) editors and numerical information processing systems c) operating systems, operating shells, drivers and utilities d) artificial intelligence systems, computer information systems, database management systems and automated control systems d) system, special, application 4. Is the controller intended? a) for transmitting processed information b) for transmitting the address of memory or external devices accessed by the processor c) for transmitting control signals d) for converting information coming from the processor into appropriate signals that control the operation of devices

Please help me solve the problems.

1. One hot summer day, Petya and his friend Vasya decided to buy a watermelon. They chose the largest and ripest, in their opinion. After a short weighing procedure, the scales showed w kilogram. Hastily running home, exhausted from thirst, the guys began to divide the purchased berries, but they were faced with a difficult task. Petya and Vasya are big fans of even numbers, so they want to divide the watermelon so that everyone’s share weighs an even number of kilograms, although it is not necessary that the shares be equal in size. The guys are very tired and want to start eating as soon as possible, so you must tell them whether it will be possible to divide the watermelon, taking into account their wishes. Of course, everyone should get a piece of positive weight.
Input data
The first and only line of the input contains an integer w (1 ≤ w ≤ 100) - the weight of the watermelon the guys bought.
Output
Print YES if the guys can divide the watermelon into two parts, each of which weighs an even number of kilograms, and NO otherwise.
Note
For example, guys can divide a watermelon into two parts measuring 2 and 6 kilograms, respectively (another option is two parts of 4 and 4 kilograms).

2. The coordinates of K buildings are given on the checkered plane. It is required to build a ring road around buildings of minimum length in the form of a rectangle, with sides parallel to the grid lines.
Input data
In the input file, on the first line, there is the number K(). The next K lines contain pairs of numbers and – the coordinates of buildings
().
Output
Output the coordinates of the lower left and upper right corners of the rectangle into the output file.

3. Hacker Ivan is an employee of a large antivirus company. One of the viruses he is researching was specifically created to attack stock trading programs.
In order to defeat the malware, Vanya needs to develop an algorithm that would calculate the minimum number of operations necessary for a pair of numbers (a, b) to become “k-beautiful”. A pair of numbers (a, b) is called “k-beautiful” if at least one of the numbers in the pair is not less than a given integer k. In this case, operations carried out with a pair of numbers (a, b) can only be the following:
1. The pair (a, b) can be converted to (a+b, b);
2. The pair (a, b) can be converted to (a, b+a).
Help Vanya win.
Input data
The single line of input contains three integers a, b and k (- 1018 ≤ x, y, m ≤ 1018).
Output
Print the minimum number of operations or the number -1 if it is impossible to make the given pair “k-beautiful”.

4. Software engineer Nadezhda is developing a compiler for a new top-secret programming language. In order to complete the development of one of the modules, she needs to solve the following problem:
In the input data, Nadya receives a string containing numbers and brackets of the same type: "(" and ")". Nadya needs to write a program that, for any input data, determines whether the bracket sequence contained in it is correct, and if the bracket sequence is correct, it returns the number of brackets found in it; if the sequence is incorrect, then the number -1 is displayed.
A bracket sequence is said to be correct if:
1. An empty string is a regular bracket sequence;
2. A regular bracket sequence taken in brackets of the same type is a regular bracket sequence;
3. A regular bracket sequence to which a regular bracket sequence is assigned to the left or right is also a regular bracket sequence.
Help Nadya develop a compiler for a new top-secret programming language.
Input data
A single finite-length line contains numbers and parentheses, and the line length is no more than 1024 characters.
Output
Print the number of brackets if the bracket sequence is correct or the number -1 if not.

5. Little Vasya learned to count the sum of digits for any number. For any number, he counted the sum of its digits, then he did the same with the resulting number, and so on. Determine how many times Vasya needs to count the sum for it to become a number.
Input data
One non-empty line with a number (0 Output
One line, with a number.

When representatives of two companies exchange business cards during business communication, the email address and the name of the company’s corporate Web site will be indicated on them (the business cards). At the same time, you can also hear how the interlocutors exchange “Internet addresses” (“electronic addresses”) of companies. In all of the above cases, one way or another we are talking about the use of domain names.

In an email address, formally, the domain name can be considered what is written after the commercial at symbol - “@”. For example, in [email protected] The domain name of the mail node is corp.ru.

The Web site name is the domain name of that site. For example, Microsoft's Web site has the domain name Microsoft.com.

In most cases, when searching for information on the Internet, we search through domain names or follow links whose notation again uses domain names.

Quite often, along with the phrase “Internet address,” “domain address” is used. Generally speaking, neither one nor the other concept exists in TCP/IP networks. There is numeric addressing, which relies on IP addresses (a group of 4 numbers separated by a ".") and the Internet service Domain Name System (DNS).

Numerical addressing is convenient for computer processing of routing tables, but is completely (here we are exaggerating somewhat) not acceptable for human use. It is much more difficult to remember sets of numbers than mnemonic meaningful names.

However, connections to exchange information on the Internet are established using IP addresses. Symbolic names of the domain name system are a service that helps to find the IP addresses of network nodes necessary to establish a connection.

However, for many users, it is the domain name that acts as the address of an information resource. In the practice of administering local networks, there are often situations when users complain to the network administrator about the inaccessibility of a particular site or long loading times of pages. The reason may lie not in the fact that the network segment has lost connection with the rest of the network, but in poor DNS performance - no IP address, no connection.

DNS hasn't been around since the birth of TCP/IP networks. At first, to facilitate interaction with remote information resources on the Internet, tables of correspondence between numeric addresses and machine names began to be used.

Modern operating systems also support tables of correspondence between the IP address and the machine name (more precisely, the host) - these are files named hosts. If we are talking about a Unix-type system, then this file is located in the /etc directory and looks like this:

127.0.0.1 localhost
144.206.130.137 polyn Polyn polyn.net.kiae.su polyn.kiae.su
144.206.160.32 polyn Polyn polyn.net.kiae.su polyn.kiae.su
144.206.160.40 apollo Apollo www.polyn.kiae.su

To access a machine, a user can use both the machine’s IP address and its name or alias. As can be seen from the example, there can be many synonyms, and, in addition, the same name can be specified for different IP addresses.

Let us remind you once again that you cannot gain any access to the resource using the mnemonic name itself. The procedure for using a name is as follows:

• first, the IP address is found in the hosts file by name,
• then a connection to a remote information resource is established using the IP address.

The calls below are similar in their effect - initiating a telnet session with the Apollo machine:

telnet 144.206.160.40

telnet www.polyn.kiae.su

In local networks, hosts files are still used quite successfully. Almost all operating systems from various Unix clones to the latest versions of Windows support this system of mapping IP addresses to host names.

However, this way of using symbolic names was fine as long as the Internet was small. As the Web grew, it became difficult to maintain large, consistent lists of names on each computer. The main problem was not even the size of the match list, but the synchronization of its contents. In order to solve this problem, DNS was invented.

DNS was described by Paul Mockapetris in 1984 in two documents: RFC-882 and RFC-883 (These documents were later replaced by RFC-1034 and RFC-1035). Paul Mockapetris also wrote the DNS implementation - the JEEVES program for the Top-20 OS. It is this that RFC-1031 suggests that administrators of machines running the Tops-20 OS of the MILNET network switch to. We will not go into detail about the contents of RFC-1034 and RFC-1035. Let's limit ourselves to only the basic concepts.

The role of the name (domain name) in the connection establishment process remains the same. This means that the main thing it is needed for is obtaining an IP address. Consistent with this role, any DNS implementation is an application process that runs on top of the TCP/IP internetworking protocol stack. Thus, the IP address remains the basic element of addressing in TCP/IP networks, and domain naming (domain name system) serves as an auxiliary service.

The domain name system is built on a hierarchical principle. More precisely, according to the principle of sets nested within each other. The root of the system is called "root" (literally translated as "root") and is not designated in any way (has an empty name according to RFC-1034).

It is often written that the designation of the root domain is the "." symbol, but this is not so, the dot is a separator for the components of the domain name, and since Since the root domain does not have a designation, the fully qualified domain name ends with a period. However, the "." is quite firmly established in the literature as a designation for the root domain. This is partly due to the fact that in the configuration files of DNS servers, this particular character is indicated in the domain name field (NAME field according to RFC-1035) in resource description records when it comes to the root domain.

The root is the entire set of Internet hosts. This set is divided into first-level or top-level domains (top-level or TLD). The ru domain, for example, corresponds to many hosts on the Russian part of the Internet. Top-level domains are split into smaller domains, for example, corporate ones.

In the 80s, the first first-level domains (top-level) were defined: gov, mil, edu, com, net. Later, when the network crossed the national borders of the United States, national domains like: uk, jp, au, ch, etc. appeared. The su domain was also allocated for the USSR. After 1991, when the republics of the Union became sovereign, many of them received their own domains: ua, ru, la, li, etc.

However, the Internet is not the USSR, and you cannot simply throw out the su domain from the domain name system. Domain names are used to build email addresses and access to many other Internet information resources. Therefore, it turned out to be much easier to introduce a new domain to an existing one than to replace it.

To be more precise, no provider currently allocates (delegates) new names with the su extension. However, many people want to resume the process of domain delegation in the SU zone.

A list of top-level domains and their types can be found, for example, in the material.

As already mentioned, after top-level domains there are domains that define either regions (msk) or organizations (kiae). Nowadays, almost any organization can get its own second-level domain. To do this, you need to send an application to the provider and receive a registration notification (see "How to get a domain").

Part of the domain naming tree can be represented as follows:

Fig.1. An example of part of a domain name tree.

The root of the tree does not have a label name. Therefore it is designated as "". The remaining nodes of the tree have labels. Each node corresponds to either a domain or a host. A host in this tree is understood as a leaf, i.e. a node below which there are no other nodes.

You can name a host either by a partial name or by a full name. A fully qualified host name is a name that lists, from left to right, the names of all intermediate nodes between the leaf and the root of the domain naming tree, starting with the leaf name and ending with the root, for example:

polyn.net.kiae.su.

A partial name is a name that lists not all, but only part of the host names, for example:

polyn
apollo.polyn
quest.polyn.kiae

Please note that partial (incomplete) names do not have a dot at the end of the name. In real life, domain name system software expands unqualified names to full names before contacting domain name servers for an IP address.

The word "Host" is not fully synonymous with the name of the computer, as is often simplified. Firstly, a computer can have many IP addresses, each of which can be associated with one or more domain names. Secondly, one domain name can be associated with several different IP addresses, which, in turn, can be assigned to different computers.

Once again, note that the naming goes from left to right, from the minimum host name (from the leaf) to the root domain name. Let's look at, for example, the full domain name demin.polyn.kiae.su. The host name is demin, the name of the domain to which this host belongs is polyn, the name of the domain that covers the polyn domain, i.e. is broader in relation to polyn, - kiae, in turn, the latter (kiae) is part of the su domain.

The name polyn.kiae.su is already a domain name. It is understood as the name of many hosts that have polyn.kiae.su in their name. Generally speaking, the name polyn.kiae.su can also have a specific IP address assigned to it. In this case, in addition to the domain name, this name will also denote the host name. This technique is often used to provide short and meaningful addresses in an email system.

Host and domain names are separated from each other in this notation by a "." character. The fully qualified domain name must end with a "." character, because the last dot separates the empty root domain name from the top-level domain name. Often in the literature and in applications, this point is omitted when writing a domain name, using the unqualified domain name notation, even when all node names from the leaf to the root of the domain name are listed.

It should be borne in mind that in real life domain names are rather bizarrely mapped to IP addresses, and even more so to real physical objects (computers, routers, switches, printers, etc.) that are connected to the network.

A computer physically installed and connected to the Network in distant America can quite easily have a name from a Russian corporate domain, for example, chalajva.ru, and vice versa, a computer or router in the Russian segment can have a name from the com domain. The latter, by the way, is much more common.

Moreover, the same computer can have multiple domain names. It is possible that several IP addresses can be assigned to one domain name, which are actually assigned to different servers serving the same type of requests. Thus, the mapping between domain names and IP addresses within the domain name system is not one-to-one, but is many-to-many.

The last few remarks were intended to draw the reader's attention to the fact that the hierarchy of the domain name system is strictly observed only in the names themselves and reflects only the nesting of naming and the areas of responsibility of the administrators of the corresponding domains.

We should also mention canonical domain names. This concept is found in the context of describing the configurations of subdomains and areas of responsibility of individual domain name servers. From the point of view of the domain tree, domain names are not divided into canonical and non-canonical, but from the point of view of administrators, servers and email systems, such a division is essential. A canonical name is a name that is explicitly associated with an IP address, and which itself is explicitly associated with an IP address. A non-canonical name is a synonym for a canonical name. See "setting up BIND" for more details.

The most popular implementation of the domain name system is the Berkeley Internet Name Domain (BIND). But this implementation is not the only one. So, Windows NT 4.0 has its own domain name server that supports the DNS specification.

However, it is advisable even for Windows administrators to know the operating principles and rules for configuring BIND, because It is this software that maintains the domain name system from the root to the TLD (Top Level Domain).

1. P. Mockapetris. RFC-1034. DOMAIN NAMES - CONCEPTS AND FACILITIES. ISI, 1987. (http://www.ietf.org/rfc/rfc1034.txt?number=1034)
2. P. Mockapetris. RFC-1035. DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION. ISI, 1987. (http://www.ietf.org/rfc/rfc1035.txt?number=1035)
3. W. Lazear. RFC-1031. MILNET NAME DOMAIN TRANSITION. 1987. (http://www.ietf.org/rfc/rfc1031.txt?number=1031)
4. Albitz P., Lee K.. DNS and BIND. - Per. from English - St. Petersburg: Symbol-Plus, 2002. - 696 p.

1. http://www.dns.net/dnsrd/docs/ - a collection of links to documents about the domain name system.
2. http://www.internic.net/faqs/authoritative-dns.html - a short description of the purpose of the domain name system.
3. http://www.icann.org/ is the website of the organization that is responsible for naming on the Internet.
4. http://www.ispras.ru/~grn/dns/index.html - G.V. Klyuchnikov. Domain Name System. 1999. In fact, this is an excellent compilation of primary sources given at the end of the book. Examples are taken from the same primary sources. Very high quality translation and well composed text.
5. http://www.ibb.ru/articles/stat_3.phtml - from the series “DNS in five minutes” J, but this material may be useful as an introduction to the topic.
6. http://www.pi2.ru:8100/prof/techsupp/dns.htm - a kind of description of the domain name system. In any case, original. But some aspects are covered quite unusually.

Solution:

The properties of the “Selection Field” object have changed: “Horizontal Position” and “Vertical Position”, as well as “Inscription” and “Selection State”. The “Horizontal Position” and “Vertical Position” of the “Button” object, as well as the “Inscription” have changed.

Task No. 31.

A device that has two network cards and is designed to connect networks is called... bridge

Solution:

Bridge(network bridge, bridge) - network hardware designed to unite various segments of a local network, serves to differentiate information flows and different segments depending on the tasks assigned.

Task N 32. The domain name of a computer can be ... abcd.eqwert.com

Solution:

The domain name of a computer is written in Latin, where all parts of the name (names of domains and the server itself) are separated by dots, for example www.rambler.ru. Here www is the server name, rambler is the second-level domain name, ru is the first-level domain name.

Task No. 33.

Remote computer control is provided by the service... Telnet

Solution:

One of the first services to become widespread in computer networks was associated with remote control of a powerful computer. This service was called Telnet.

Task No. 34.

A malicious program that gets onto a computer under the guise of being harmless and cannot reproduce itself is...

Solution:

Malicious programs that enter your computer disguised as harmless programs are called Trojans. Trojans do not have their own propagation mechanism and this differs from viruses, which spread by attaching themselves to programs or documents, and from worms, which copy themselves over the network.

Task No. 1.

The amount of information in the word “Informatics”, provided that a 32-digit alphabet is used for encoding, is equal to _______ bit(s).

Solution:

The amount of information that one character can contain N- elemental alphabet is equal to This is the well-known formula of R. Hartley. In a 32-character alphabet, each character carries information. The word "Informatics" has 11 characters. The amount of information in the word “Informatics” when encoded in a 32-digit alphabet is equal to

Task No. 2.

Using one byte in binary encoding, you can represent a non-negative integer from zero to...

Solution:

1 byte is equal to 8 bits, i.e. 8 binary digits. 255.

The number of different single-byte binary codes (00000000, 00000001, 00000010,…, 00110010,…, 11111111) is .

Therefore, these codes can represent 256 different numbers, for example, the numbers 0, 1, 2, 3, ..., 255. So, the maximum number that can be represented with the one-byte binary code “11111111” is equal to

Solution:

Task No. 3.

Convert the binary number 1100101001101010111 to the octal number system.

There are two possible solutions. In the first option, two main algorithms are used: first, an algorithm for converting numbers from P-ary s. With. to 10-point, and then from 10-point s. With. to Q-person. If the base of the q-ary number system is a power of 2, then the conversion of numbers from the q-ary number system to the 2-ary number system and vice versa can be carried out according to simpler rules. Algorithm for converting binary integer numbers into a base 1 number system. Divide the binary number from right to left into groups of n each. 2. If the last left group contains less than n digits, then it must be supplemented on the left with zeros to the required number of digits. 3. Consider each group as an n-bit binary number and write it with the corresponding digit in the radix number system. We divide the number 1100101001101010111 into groups of three digits - triads (since,,) from left to right and, using the table, write the corresponding octal number. We get: (without the eight) Task No. 4.

Solution: The figure shows a truth table for an expression containing two logical operations. One of them is (second column). WITH The header of the third column of the table must contain a Boolean expression...

It is necessary to recall the definition of disjunction ().

The result of a propositional disjunction operation is true if and only if at least one of the propositions is true. Turning to the answers presented in the task, you can notice that all operations are performed relative to the compound statement and statement . a logical expression of three arguments is indicated: A fragment of the truth table of the expression is given .: Logical function F corresponds to a logical expression...

Solution:

It is necessary to determine the value of F on given three sets of values ​​of logical variables. Let's substitute the values ​​of logical variables to a Boolean expression .. and in the table we substitute the second set of values ​​of logical variables to a Boolean expression .. and in the table When substituting the third set of values ​​of logical variables to a Boolean expression . and in the table. Thus, with the same sets of values ​​of logical variables, the values ​​of the logical expression and the values ​​of the logical function . match up. So the correct answer is

Task No. 7.

A processor architecture based on the concept of “smaller, simpler instructions execute faster” is a ________ architecture.

Solution:

The principle “more compact and simple instructions are executed faster” corresponds to RISC architecture processors. RISC Reduced Instructions Set Computer) – a computer with a reduced set of commands. A simple architecture makes it possible to reduce the cost of the processor, increase the clock frequency, and also parallelize the execution of commands between several execution units. The first RISC processors were developed in the early 1980s at Stanford and the University of California in the USA. They executed a small (50–100) set of commands.

Task No. 8.

Computer COM ports provide...

Solution:

COM ports are used to connect the computer with external devices and provide synchronous or asynchronous serial bit-by-bit data transfer. In general, they are bidirectional. Previously, the serial port was used to connect a modem or mouse. Now it is used to connect to uninterruptible power supplies, to communicate with hardware for the development of embedded computing systems.

Task No. 9.

Initial testing and computer boot programs are stored...

Solution:

Programs for initial testing, booting, and the basic input/output system of a personal computer are stored in a read-only memory (ROM) chip located on the system board. This is necessary so that the computer can begin to function after turning on the power, regardless of the presence and composition of additional types of memory, such as a hard drive, CD-ROM, etc.

Task No. 10.

Coordinate input devices include... mouse, joystick, trackball

Task No. 11.

Establish a correspondence between the classes of utility software and the names of specific programs. 1. File managers (file managers) Total Commander 2. Data compression tools (archivers) WinZip 3. Computer security tools DrWeb 4. Viewers and conversion tools Adobe Reader

Solution:

Utilities are programs used to perform auxiliary functions, such as working with files and folders, diagnosing hardware, viewing and converting files, optimizing disk space, restoring damaged information, antivirus tools, etc. File Managers(file managers). With their help, most operations on maintaining the file structure are performed: copying, moving, renaming files, creating directories (folders), destroying objects, searching for files and navigating in the file structure. Basic software is contained in system-level programs and is installed along with the operating system (Far Manager, Total Commander, Frigate). Data compression tools(archivers). Designed for creating archives. Archive files have an increased density of information recording and, accordingly, use storage media more efficiently (WinZip, WinRAR). Viewers and conversion tools. To work with files, they must be loaded into the native application program and the necessary corrections made. But, if editing is not needed, there are universal tools for viewing (text and pictures) or playing (music or video) data. Recently, technical documentation has been supplied in . PDF. To work with this format, there is the Acrobat Reader program from Adobe. Computer Security Tools. These include means of passive and active data protection from damage, unauthorized access, viewing and modification of data. Passive protection tools are utilities designed for backup purposes. Active protection means use antivirus software. To protect data from unauthorized access, viewing and changing, special systems based on cryptography are used.

Task No. 12.

Dialog window Seal does not contain such a control as...

Solution:

A dialog box is a window that appears on the screen when you enter a command, the execution of which requires additional information. Using the dialog box, the user enters the data necessary for further operation of the program. Dialog boxes contain the following controls: Tabs (bookmarks)– are intended to perform certain functions or commands in the window. Button– a control element in the user interface that is designed to execute commands. Field– a control element intended for entering and editing text information. Counter– a control designed to increase or decrease a numeric value in an associated text field. List– allows you to select an item from the list or enter data manually. The current value is displayed in the field, and a list of possible values ​​is expanded when you click the arrow button. Switches (radio buttons)– are used to provide the opportunity to choose one of mutually exclusive options. Checkboxes– used to select one or more items from the proposed list; are a box that the user can mark with a checkmark. To cancel the action, simply click on the square again. Slider(regulator) – sets one of the positions on the scale by moving the slider (more, less).

Task No. 13.

If the cluster size on the hard disk is 512 bytes, and the file size is 864 bytes, then _______ cluster(s) will be allocated for it on the disk (that is, inaccessible to other files).

Solution:

All modern operating systems provide the creation of a file system designed to store data on external media and provide access to it. Each hard drive consists of a stack of platters. On each side of each plate there are concentric rings called tracks. Each track is divided into fragments called sectors, and all tracks on the disk have the same number of sectors. A sector is the smallest physical unit of data storage on external media. The sector size is always a power of 2, and is almost always 512 bytes. Groups of sectors are conditionally combined into clusters. A cluster is the smallest unit of data addressing. When a file is written to disk, the file system allocates an appropriate number of clusters to store the file's data. For example, if each cluster is 512 bytes, and the size of the file being saved is 800 bytes, then two clusters will be allocated to store it. Subsequently, if you modify the file in such a way that it increases in size, say, to 1600 bytes, additional resources will be allocated to save it. two clusters. If there are no adjacent clusters on the disk (by adjacent we mean clusters located close to each other, one after the other), those clusters that exist will be allocated to save the file. And then the file will be fragmented, that is, individual fragments of the file will be located in different places on the disk. Nothing else can be placed in a cluster that is partially occupied by a file. Let's say your file is located in 10 clusters of 1024 KB in size, and in the last - tenth cluster it occupies only ten bytes. What happens to the remaining almost free kilobyte? Nothing. It simply disappears for the user.

Task No. 14.

Activating the mode shown in the figure in Microsoft Office Word allows the user to see...

Solution:

Using the “Show all characters” button you can hide or show non-printing formatting marks in a Microsoft Office Word document. Enabling the display of formatting marks on the screen results in the display of tabs as arrows, spaces between words as dots, ends of paragraphs as paragraph marks, etc. Unless additional settings have been made by the user, these formatting marks are not printable.

Task No. 15.

Solution:

The IF function has the following syntax: =IF(logical_expression, value_if_true, value_if_false). A Boolean expression is any value or expression that evaluates to TRUE or FALSE. Value_if_true - The value that is returned if the Boolean_expression argument evaluates to TRUE. Value_if_false is the value that is returned if the "Boolean_expression" evaluates to FALSE. The MAX function returns the largest value from a set of values. Syntax MAX(number1,number2, ...) Number1, number2,... – from 1 to 255 numbers, among which you want to find the largest. After carrying out the calculations using the formula in cell C3, the result will be 24. Because. the value 0 is entered into cell B5, then the value cell C3 is greater than the value in cell B5.

Task No. 16.

Given a fragment of a spreadsheet Next table

obtained from the original by sorting...

Solution:

If you need to sort a list by several fields, then the mode is intended for this Custom sorting. You can add fields using the button Add level. For example, for a table in the window Sorting sorting is carried out first by the Salary column, if the values ​​​​in the column coincide Salary– by column Full name, and if the first letters of the surnames match - according to the column Age.
In the first field ( Sort by) you should specify the column at the top sorting level. As a rule, columns with duplicate records are selected for the first levels. When you sort a record in such columns grouped. Sorting by the column specified in the second field is performed within the sorted data groups of the first column. For each field you need to specify the sort order - Ascending or descending. Comparing the two tables in the proposed problem, you can notice that in the second table the data is ordered in descending order of the values ​​in the column Rating, and in the case of equal values ​​- in alphabetical order of the values ​​in the column Full name. Therefore, the original table first you need to sort by columnRating (column C) and, without leaving the sorting mode, by columnFull name (column B). Column No.(column A) is not involved in sorting at all.

Task No. 17.

An independent minimal image element in raster graphics, from the set of which an image is built, is called... pixel(dot)

Task No. 18.

A presentation file that will always open only in slide show mode is...

Solution:

Format. pps provides for saving a presentation that will always open in slide show mode. Show mode automatically launches a full-screen demonstration with the settings set in slide sorter mode.

Task No. 20.

A means of graphically displaying the logical structure of a database “data diagram”
allows...

Solution:

Table linking is used to avoid duplicate data. For example, if you include the fields CUSTOMER NAME, PRODUCT NAME, PRICE in the ORDERS table, then when filling out such a table for each order you will have to indicate a rather long customer name, product name and price, which is very inconvenient. Moreover, any minor error when entering these fields (for example, different prices are entered for the same product) will lead to a violation of the consistency of the database. In this case, proceed as follows: enter the CLIENT CODE field (integer) into the ORDERS table and add another CLIENTS table with the fields CLIENT CODE, CLIENT NAME. The CLIENTS and ORDERS tables are linked by the CLIENT CODE field. The same applies to the ORDERS and PRODUCTS tables.

Task No. 21.

Indicate the correct order of the stages of computer modeling: a) planning and conducting computer experiments, b) creating an algorithm and writing a program, c) developing a conceptual model, identifying the main elements of the system and their relationships, d) formalization, transition to a model, e) problem statement , definition of the modeling object, f) analysis and interpretation of the results.

d); V); G); b); A); e)

Solution:

Modeling occupies a central place in the study of an object. Building a model allows you to make decisions on improving existing facilities and creating new ones, changing their management processes and changing the world around us for the better. All stages of modeling are determined by the task and goals. Modeling begins with the statement of the problem, which is description of the problem, definition of the modeling object and modeling goals, which allows you to determine what data is the source and what you want to get as an output. The model development phase begins with constructing a conceptual (information) model in various symbolic forms. In information models, the problem takes on a form that allows one to make a decision on choosing a software environment and present algorithm for constructing a computer model. The choice of software environment determines the algorithm for constructing a computer model, as well as the form of its presentation. For example, it can be a flowchart; in a programming environment, it is a program written in an algorithmic language; in applied environments, it is a sequence of technological techniques that leads to solving a problem. A variety of software allows transform the original information sign model in computer and conduct a computer experiment. A computer experiment is the influence on a computer model using software environment tools in order to determine how the model parameters change. Preparing and conducting a computer experiment includes a number of sequential operations related to testing the model, developing an experimental plan, and actually conducting the research. The ultimate goal of modeling is decision-making, which should be developed on the basis of a comprehensive analysis of the modeling results and interpretation of its results.

Task No. 22.

A descriptive information model is(are)… heliocentric model of the world

Task No. 24.

When conducting classes, the projector turns on at the beginning of the lesson and turns off 10 minutes after the end of the lesson. The class schedule for the current day is shown in the figure. The maximum rest time for the projector (with the power off) is ________minutes.

Solution:

After the first pair, the projector will turn off at 9:30 (since it turns off 10 minutes after the end of the pair), therefore, the computer's rest time between the first and second pair will be 5 minutes; after the second pair, the projector will turn off at 11:25, therefore, the computer's rest time between the second and third pair will be 55 minutes; after the third pair, the projector will turn off at 14:05, therefore, the computer's rest time between the third and fourth pair will be 40 minutes; Thus, we find that the maximum rest time will be 55 minutes.

Task No. 25. The statement is true that... any compiler is a translator

Solution:

Using a programming language, it is not a finished program that is created, but only its text, which describes a previously developed algorithm. This text is then used by special utility applications called broadcasters, is either automatically translated into machine code or executed. The process of converting the statements of the source programming language into machine codes of the microprocessor is called broadcast source text. The broadcast is made by special broadcasting programs. Translators are implemented as compilers and interpreters.

Task No. 26.

Variable value ., if the initial values ​​of the variables A, B And C are equal to 1, 1 and 4, respectively, will be equal to ... 6

Solution:

If A, B And C are equal to 1, 1 and 4, respectively, then after checking the conditions A=IN the process will follow the arrow “yes” and further after checking the condition IN>WITH by the arrow "no". The next block calculates A=A+IN=1+1=2 and so on .=A+WITH=2+4=6.

Task No. 27.

Select the correct notation for the expression in the programming language.

Solution:

An expression in a programming language specifies a rule for calculating a certain value. An expression consists of constants, variables, function pointers, operator signs, and parentheses. Each expression has a type that depends on the types of its operands. The expression is called arithmetic, if its value is a number. Arithmetic expression is written to a string. You cannot place two signs of arithmetic operations in a row. You cannot omit the multiplication sign. Examples of writing arithmetic expressions: When calculating the values ​​of expressions, the order in which the operations are performed is important. The following rules have been adopted. Actions are performed from left to right, observing the following precedence (in descending order): 1) actions in parentheses; 2) calculation of functions; 3) NOT; 4) *, /, DIV, MOD, AND; 5) +, -, OR; 6) =,<>, <, >, <=, >=. If the priority of operations is the same, then the operation to the left is executed first. The order of operations can be overridden by using parentheses. For example, equal to 20, but equal to 30. When writing expressions containing parentheses, the pairing of parentheses must be observed, i.e. The number of opening parentheses must be equal to the number of closing parentheses.

Task No. 28

Show the program fragment corresponding to the given fragment of the algorithm. Solution:

The branching design is a basic algorithmic design and provides a choice between two alternatives depending on the input data. First it is checked condition(a logical expression is evaluated). If the condition is true, then actions 1– a sequence of commands indicated by an arrow labeled “yes” (positive branch). Otherwise, actions 2 (negative branch) are performed. There are complete and incomplete branching. Full branching allows you to organize two branches in an algorithm, each of which leads to a common point of their merger, so that the execution of the algorithm continues regardless of which branch was chosen. If condition That actions 1 otherwise actions 2 All The proposed problem uses the full branching option. First checked Condition 1 Episode 1. If it is false, it is checked Condition 2. If it is true, then it is executed Episode 2, otherwise Episode 3, those. If Condition 1 That Episode 1 otherwise If Condition 2 That episode 2 otherwise episode 3 everything everything