How to solve the exam in computer science. How to solve exam tasks in computer science

The USE in Informatics is not a mandatory test for all school graduates, but is required for admission to a number of technical universities. This exam is rarely taken, since there are few higher education institutions where it is required. A common case when entering a number of specialties in polytechnic universities is the opportunity to choose between physics and computer science. In such a situation, many choose the latter, since physics is rightly considered to be a more complex discipline. Knowledge of computer science will be useful not only for admission, but also in the process of mastering a specialty in a higher educational institution.


The main feature of the school subject "Computer Science" is a small volume, therefore, for high-quality preparation, less time is needed than for other subjects. It is possible to prepare "from scratch"! To compensate for the small amount of material, the authors of questions and tasks offer subjects difficult tasks, tasks that provoke errors, require high-quality knowledge of information and its competent use. The content of the exam contains a significant number of tasks that come close to the knowledge of mathematics and logic. A significant part is the block of tasks for algorithmization, tasks, programming. Check out
All tasks can be divided into 2 blocks - testing (tasks for knowledge of theory, a short answer is required), detailed tasks. It is recommended to spend about an hour and a half on the first part, more than two on the second. Take the time to check for errors and fill in the answers on the form.
To learn how to easily overcome obstacles in the form of complex tasks, use the resource "I will solve the exam". This is a great opportunity to test yourself, consolidate knowledge, analyze your own mistakes. Regular online testing will relieve anxiety and worry about lack of time. The tasks here are mostly more difficult than on the exam.


  • It is recommended that you carefully read the USE preparation program - this will make the repetition process systematic and structured to learn the theory.
  • To date, many training aids have been developed - use them to practice and study the material.
  • Learn to solve problems of different types - it's easier to do with the help of a tutor. If you have a high level of knowledge, you can cope on your own.
  • Decide for a time when you have mastered the necessary data and learned how to solve problems. Online testing will help with this.
What to do if the initial knowledge is weak?
  • It is important not to miss opportunities for preparation: courses, schooling, distance courses, tutoring, self-education. Outline the range of problems that cause the greatest number of questions and difficulties.
  • Practice in solving problems - the more the better.
  • Correctly allocate time to work with tasks of different levels of complexity.
  • Find a professional tutor to help fill in knowledge gaps.

Lada Esakova

When a student of grade 11 begins to prepare for the exam in computer science, as a rule, he prepares from scratch. This is one of the differences between the exam in computer science and exams in other subjects.

In mathematics, the knowledge of a high school student is definitely not zero. In Russian, even more so.

But in computer science, the situation is much more complicated. What is studied at school in the classroom has nothing to do with the preparation program for the exam in computer science.

What is the USE in Informatics?

The USE control test in computer science contains 27 tasks, which relate to a variety of topics. These are number systems, this is Boolean algebra, algorithmics, this is programming, modeling, elements of graph theory.

The USE in Informatics covers a very wide range of information. Of course, the exam will only need the basics, but these are the basics of important and modern topics.

Preparing for the Unified State Exam in computer science from scratch implies that the student did not study any of these topics at school. Usually it is!

For example, such a topic as Boolean algebra, or the algebra of logic, is included in the exam in computer science. But it is not studied in schools, even in specialized ones. She is neither in the course of school computer science, nor in the course of mathematics. The student has no idea!

And therefore, almost none of the students solves the famous problem on systems of logical equations. This task in the Unified State Examination in Informatics is number 23. Let's say more - teachers often recommend that high school students not try to solve this problem at all, and not even look at it, so as not to waste time.

Does this mean that task 23 from the Unified State Examination in Informatics is not solved at all? Of course not! Our students regularly solve it every year. In our course of preparation for the Unified State Examination in Informatics, from many topics, we take only what is required for the exam. And we pay maximum attention to these tasks.

Why does the school not prepare for the exam in computer science?

This is due to the fact that computer science is not a compulsory subject. The Ministry of Education does not provide any standards and programs. Therefore, teachers at computer science lessons give schoolchildren completely different material - who can do what. Moreover, in some schools there are no computer science lessons at all.

What do high school students usually do in computer science classes? Do they play shooting games?

Fortunately, at school, in computer science lessons, schoolchildren are still doing not nonsense, but quite useful things. For example, they study Word and Escel. In life, this will come in handy, but, unfortunately, it is absolutely useless for passing the exam.

Moreover, the guys study Word at a serious level, and some even pass exams in computer layout and receive a certificate of a typesetter. Some schools teach 3D modeling. A lot of schools give web design. This is a wonderful topic, useful in the future, but it has nothing to do with the exam! And coming to our courses, the student really prepares for the exam in computer science from scratch.

A similar situation is with high school students of specialized lyceums. Strong profile lyceums honestly teach programming in computer science lessons. The guys come out of there as good programmers. But after all, in the USE in computer science, only 5 tasks are somehow related to programming, and of them exactly one task in the USE version is devoted to writing a program! The result is a maximum of 6 tasks for the exam in computer science.

How much time does it take to prepare for the exam in computer science from scratch?

There is good news! You can prepare for the exam in computer science from scratch in one year. It's not easy, but it's possible, and our students prove it every year. The course of preparation for the exam in computer science is not very large. You can take courses once a week for 2 hours. Of course, you need to actively do your homework.

But there is one amendment. If a student has never done programming before grade 11, it is hardly possible to fully master programming in a year. Therefore, task No. 27 of the USE variant in computer science will remain unsolved. She is the most difficult.

It is especially difficult to prepare for the exam in computer science from scratch for those students who have never been familiar with programming at all and do not know what it is. This area is quite specific, so programming training needs to be given a lot of time and solve a huge number of tasks.

In our courses, we make sure to analyze all the typical programming tasks. And not once during the exam did the programming problem come as a surprise to our students - they were all sorted out during the courses. And only task 27 is left out for those who did not do programming at all until the 11th grade.

Coming to our computer science courses, students and parents are sometimes surprised not to see computers in the classroom. They think that since they came to prepare for the exam in computer science, then there should be computers on the tables. But they are not! To what extent is it necessary to have laptops and computers when preparing for the exam in computer science?

This is a feature of the exam in computer science. There will be no computer for the exam! And yes, it will be necessary to solve tasks with a pen on a sheet of paper, because it is in this format that the Unified State Examination in Informatics is now taking place. This is a real problem for those who rent it.

Even high school students from specialized lyceums, who are good at programming, may be helpless at the exam in computer science. They, of course, program on computers, that is, in a special environment. But what happens when there is no computer? And not only schoolchildren - even professional programmers can write a program on paper with great difficulty. Therefore, we are preparing for such a complex format right away. We deliberately do not use computers and laptops when preparing for the Unified State Exam in computer science - according to the rule "It is hard in learning, easy in battle."

For several years now, there have been rumors that the Unified State Exam in computer science will be transferred to a computer form. They promised to do it in 2017, but they didn't. Will they do it in 2018? We don't know yet. If such an exam format is introduced, it will be much easier to prepare for the exam in computer science from scratch.

So, a year of active preparation for the exam in computer science from scratch, and your result is 26 tasks out of 27 possible. And if you are at least a little familiar with programming, then all 27 out of 27. We wish you to achieve such a result in the exam!

And once again I recommend for the preparation of theoretical material and my book "Computer science. Author's course of preparation for the exam " where the practice of problem solving is given.

Tell your friends!

This exam lasts 4 hours. Maximum amount points scored - 35. The percentage ratio between the levels of questions is almost equal. Most of the questions are test questions, in the exam only 4 tasks are assigned for a detailed answer.

Computer science exam is quite complex and requires special attention and proper preparation of students. It includes general test questions which are designed for low level knowledge. There are also tasks that require reflection and calculations with an accurate calculation.

The distribution of tasks in parts of the exam paper of the Unified State Examination of 2019 in computer science, indicating the primary scores below in the infographic.

Maximum points - 35 (100%)

Total exam time - 235 minutes

66%

Part 1

23 tasks 1-23
(with short answer)

34%

Part 2

4 tasks 1-4
(Detailed response)

Changes in KIM USE 2019 compared to 2018

  1. There are no changes in the CIM structure. In task 25, the possibility of writing an algorithm in natural language was removed due to the lack of demand for this possibility by the exam participants.
  2. Examples of program texts and their fragments in the conditions of tasks 8, 11, 19, 20, 21, 24, 25 in the C language are replaced with examples in the C ++ language, as it is much more relevant and common.

Systematic preparation is the key to success

The educational portal site offers many demonstration computer science tests that you can solve without leaving your workplace.

Trial tasks will help you plunge into the atmosphere of testing and find those knowledge gaps that need to be corrected to achieve maximum results.

For high school graduates. It must be taken by those who plan to enter universities for the most promising specialties, such as information security, automation and control, nanotechnology, systems analysis and control, rocket systems and astronautics, nuclear physics and technology, and many others.

Read the general information about the exam and start preparing. There are practically no changes compared to last year in the new version of KIM USE 2019. The only thing is that fragments of programs written in the C language disappeared from the tasks: they were replaced with fragments written in the C++ language. And from task number 25, they removed the opportunity to write an algorithm in natural language as an answer.

USE score

Last year, in order to pass the Unified State Examination in Informatics, at least for a three, it was enough to score 42 primary points. They were given, for example, for the correctly completed first 9 tasks of the test.

How it will be in 2019 is still not known for sure: you need to wait for an official order from Rosobrnadzor on the correspondence of primary and test scores. Most likely it will appear in December. Considering that the maximum primary score for the entire test has remained the same, the minimum score will most likely not change either. Let's take a look at these tables:

USE test structure

Informatics is the longest exam (the same is the duration of the exam in mathematics and literature), the duration is 4 hours.

In 2019, the test consists of two parts, including 27 tasks.

  • Part 1: 23 tasks (1-23) with a short answer, which is a number, a sequence of letters or numbers.
  • Part 2: 4 tasks (24–27) with a detailed answer, the full solution of the tasks is recorded on the answer sheet 2.

All tasks are connected in one way or another with a computer, but it is not allowed to use it to write a program in group C tasks during the exam. In addition, the tasks do not require complex mathematical calculations and the use of a calculator is also not allowed.

Preparation for the exam

  • Pass the USE tests online for free without registration and SMS. The presented tests are identical in their complexity and structure to the real exams held in the corresponding years.
  • Download demo versions of the Unified State Examination in Informatics, which will allow you to better prepare for the exam and make it easier to pass it. All proposed tests were developed and approved for preparation for the Unified State Examination by the Federal Institute of Pedagogical Measurements (FIPI). In the same FIPI, all official versions of the exam are being developed.
    The tasks that you will see, most likely, will not be found on the exam, but there will be tasks similar to the demo ones, on the same topic or simply with different numbers.

General USE numbers

Year Min. USE score Average score Number of applicants Did not pass, % Qty
100 points
Duration-
exam length, min.
2009 36
2010 41 62,74 62 652 7,2 90 240
2011 40 59,74 51 180 9,8 31 240
2012 40 60,3 61 453 11,1 315 240
2013 40 63,1 58 851 8,6 563 240
2014 40 57,1 235
2015 40 53,6 235
2016 40 235
2017 40 235
2018

Option No. 3490088

When completing tasks with a short answer, enter in the answer field the number that corresponds to the number of the correct answer, or a number, a word, a sequence of letters (words) or numbers. The answer should be written without spaces or any additional characters. Separate the fractional part from the whole decimal point. Units of measurement are not required.


If the option is set by the teacher, you can enter or upload answers to the tasks with a detailed answer into the system. The teacher will see the results of the short answer assignments and will be able to grade the uploaded answers to the long answer assignments. The points given by the teacher will be displayed in your statistics.


Version for printing and copying in MS Word

Specify the smallest four-digit hexadecimal number whose binary notation contains exactly 5 zeros. In your answer, write down only the hexadecimal number itself, you do not need to indicate the base of the number system.

Answer:

A fragment of the truth table of the expression F is given:

x1x2x3x4x5x6x7x8F
1 0 1 0 1 1 1 0 0
0 1 0 1 1 0 0 1 0
1 0 0 1 0 1 0 1 1

Which of the following expressions can be F?

1) (x2→x1) ∧ ¬x3 ∧ x4 ∧ ¬x5 ∧ x6 ∧ ¬x7 ∧ x8

2) (x2→x1) ∨ ¬x3 ∨ x4 ∨ ¬x5 ∨ x6 ∨ ¬x7 ∨ x8

3) ¬(x2→x1) ∨ x3 ∨ ¬x4 ∨ x5 ∨ ¬x6 ∨ x7 ∨ ¬x8

4) (x2→x1) ∧ x3 ∧ ¬x4 ∧ x5 ∧ ¬x6 ∧ x7 ∧ ¬x8

Answer:

Roads were built between settlements A, B, C, D, E, F, the length of which is shown in the table. The absence of a number in the table means that there is no direct road between the points.

ABCDEF
A 2 4 8 16
B2 3
C4 3
D8 3 3 5 3
E 5 5
F16 3 5

Determine the length of the shortest path between points A and F, passing through point E and not passing through point B. You can only move along the indicated roads.

Answer:

For batch operations with files, file name masks are used. The mask is a sequence of letters, numbers, and other characters allowed in file names, which may also contain the following characters:

symbol "?" () question mark means exactly one arbitrary character.

the symbol "*" (asterisk) means any sequence of characters of arbitrary length, including "*" can also specify an empty sequence.

The directory contains 6 files:

Determine which mask will be used to select the specified group of files from the directory:

Answer:

A 5-bit code is used to transmit data over a communication channel. The message contains only the letters A, B and C, which are encoded with the following code words:

A - 11111, B - 00011, C - 00100.

Transmission may be interrupted. However, some errors can be corrected. Any two of these three code words differ from each other in at least three positions. Therefore, if the transmission of a word has an error in no more than one position, then an educated guess can be made about which letter was transmitted. (It is said that “the code corrects one error.”) For example, if codeword 10111 is received, it is considered that the letter A was transmitted. (The difference from the codeword for A is only in one position, there are more differences for the remaining codewords.) If the received codeword word differs from the code words for the letters A, B, C in more than one position, then it is considered that an error has occurred (it is denoted by "x").

Answer:

The automaton receives a four-digit number as input (the number cannot start from zero). Based on this number, a new number is constructed according to the following rules.

1. The first and second, second and third, third and fourth digits of a given number are added separately.

2. The smallest of the received three amounts is removed.

3. The remaining two amounts are written one after the other in non-decreasing order without separators.

Example. Original number: 1984. Sums: 1 + 9 = 10, 9 + 8 = 17, 8 + 4 = 12.

10 is removed. Result: 1217.

Specify least number, upon processing of which the machine produces the result 613.

Answer:

A fragment of a spreadsheet is given.

ABCDEF
1
2 1 10 100 1000
3 2 20 200 2000
4 3 30 300 3000
5 4 40 400 4000
6 5 50 500 5000

In cell B2, we wrote the formula =D$4 + $F3. After that, cell B2 was copied into cell A3. What number will be shown in cell A3?

Note: The $ sign is used to denote absolute addressing.

Answer:

Write down the number that will be printed as a result of the following program. For your convenience, the program is presented in five programming languages.

Answer:

Produced four-channel (quad) sound recording with a sampling rate of 32 kHz and 32-bit resolution. The recording lasts 3 minutes, its results are written to a file, data compression is not performed. Determine the approximate size of the resulting file (in MB). Give your answer as the closest integer multiple of five to the file size.

Answer:

The code lock cipher is a sequence of five characters, each of which is a digit from 1 to 5. How many different cipher options can be given if it is known that the digit 1 occurs exactly three times, and each of the other valid digits can occur in the cipher any number once or not meet at all?

Answer:

Below, a recursive algorithm is written in five programming languages F.

As an answer, indicate the sequence of digits that will be printed on the screen as a result of calling F(5).

Answer:

In the terminology of TCP / IP networks, a subnet mask is a 32-bit binary number that determines which bits of the computer's IP address are common to the entire subnet - there is a 1 in these bits of the mask. Usually masks are written as four decimal numbers - according to the same rules as well as IP addresses. For some subnet, the mask is 255.255.248.0. How many different computer addresses does this mask allow?

Note. In practice, two addresses are not used to address computers: the network address and the broadcast address.

Answer:

The car number consists of several letters (the number of letters is the same in all numbers), followed by 4 digits. This uses 10 numbers and only 5 letters: P, O, M, A, N. You need to have at least 1,000,000 different numbers. What is the minimum number of letters that should be in a car number?

Answer:

The performer CAR "lives" in a limited rectangular labyrinth on a checkered plane, shown in the figure. Gray cells - erected walls, light - free cells, on which the CAR can move freely. Along the edge of the field of the labyrinth there is also an erected wall with numbers and letters applied to identify the cells in the maze.

Command system of the executor MACHINKA:

When any of these commands is executed, the CAR moves one cell respectively (in relation to the observer): up, down ↓, left ←, right →.

Four commands check the truth of the condition of the absence of a wall on each side of the cell where the CAR is located (also in relation to the observer):

BYE<условие>team

is executed while the condition is true, otherwise it moves to the next line.

When you try to move to any gray cell, the CAR crashes against the wall.

How many cells of the given labyrinth meet the requirement that, having started in it and executing the program proposed below, the MACHINE will not crash?

BYE<снизу свободно>down

BYE<слева свободно>to the left

Answer:

The figure shows a diagram of roads connecting cities A, B, C, D, D, E, K, L, M, N, P, R, T. You can move along each road only in one direction, indicated by the arrow.

How many different ways are there from city A to city T?

Answer:

In the base number system N the record of the number 87 10 ends with 2 and contains no more than two digits. List all applicable values ​​separated by commas in ascending order N.

Answer:

In the search engine query language, the symbol "|" is used to indicate the logical operation "OR", and the symbol "&" is used for the logical operation "AND".

The table shows queries and the number of pages found by them for a certain segment of the Internet.

RequestPages found (in thousands)
France & Germany 274
Germany & (France | Austria) 467
France & Germany & Austria 104

How many pages (in thousands) will be found for the query Germany & Austria?

It is assumed that all requests were executed almost simultaneously, so that the set of pages containing all the searched words did not change during the execution of the requests.

Answer:

Denote by m&n the bitwise conjunction of non-negative integers m And n.

So, for example, 14&5 = 1110 2 &0101 2 = 0100 2 = 4.

For what is the smallest non-negative integer A the formula

x&51 = 0 ∨ (x&41 = 0 → x&A = 0)

is identically true (i.e., takes the value 1 for any non-negative integer value of the variable x)?

Answer:

Below is a fragment of the same program written in different programming languages. The program describes a one-dimensional integer array A; in the presented fragment, array elements with indices from 1 to 10 are processed.

Before starting the program, these array elements had the values ​​0, 1, 2, 3, 4, 5, 4, 3, 2, 1 (i.e. A = 0; A = 1; ...; A = 1).

Which of these array elements will have the largest value after the execution of the program fragment? In your answer, indicate the index of the element - a number from 1 to 10.

Answer:

The algorithm is written in five languages ​​below. Having received the number x as input, this algorithm prints two numbers: a and b. Specify the smallest of such numbers x, when entered, the algorithm prints first 3, and then 12.

Answer:

Write in your answer the largest value of the input variable k, at which the program produces the same answer as with the input value k= 20. For your convenience, the program is presented in five programming languages.

Answer:

The Calculator executor has two commands:

1. add 4,

2. subtract 2.

The first of them increases the number on the screen by 4, the second - reduces it by 2. If a negative number appears during the calculation, it fails and erases what is written on the screen. A calculator program is a sequence of commands. How many different numbers can be obtained from the number 8 using a program that contains exactly 16 instructions?

Answer:

How many different sets of values ​​of boolean variables x1, x2, x3, x4, x5, x6, x7, x8, x9, x10 are there that satisfy all of the following conditions:

((x1 → x2) → (x3 → x4)) ∧ ((x3 → x4) → (x5 → x6)) = 1;

((x5 → x6) → (x7 → x8)) ∧ ((x7 → x8) → (x9 → x10)) = 1;

x1∧x3∧x5∧x7∧x9 = 1.

The answer does not need to list all the different sets of values ​​of the variables x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, under which the given system of equalities is satisfied. As an answer, you need to indicate the number of such sets.

Answer:

It was necessary to write a program that enters from the keyboard the coordinates of a point on a plane ( x, y are real numbers) and determines whether a point belongs to the shaded area. The programmer was in a hurry and wrote the program incorrectly.

Do the following in sequence:

1. Redraw and complete the table that shows how the program works with arguments belonging to different areas (A, B, C, D, E, F, G, and H).

Points lying on the boundaries of the regions are not considered separately. In the condition columns, enter "yes" if the condition is met, "no" if the condition is not met, "-" (dash) if the condition will not be checked, "not known" if the program behaves differently for different values belonging to this area. In the "Program will output" column, specify what the program will display on the screen. If the program does not display anything, write "-" (dash). If different texts are displayed for different values ​​belonging to the area, write "not known". Enter "yes" or "no" in the last column.

2. Indicate how the program needs to be improved so that there are no cases of its incorrect operation. (This can be done in several ways, just specify any way to refine the original program.)

Two players, Petya and Vanya, play the following game. There is a pile of stones in front of the players. Players move in turn, Petya makes the first move. In one move, the player can add one or three stones to the pile, or double the number of stones in the pile. For example, having a pile of 15 stones, in one move you can get a pile of 16, 18 or 30 stones. Each player has an unlimited number of stones to make moves. The game ends when the number of stones in the pile becomes at least 35. The winner is the player who made the last move, i.e. the first to receive a pile that will contain 35 or more stones. At the initial moment, there were S stones in the heap; 1 ≤ S ≤ 34. We will say that a player has a winning strategy if he can win for any moves of the opponent. To describe a player's strategy means to describe what move he should make in any situation that he may encounter with different opponent's play.

Complete the following tasks. In all cases, justify your answer.

Exercise 1

a) Indicate all such values ​​of the number S for which Petya can win in one move. Justify that all the required values ​​of S are found, and indicate the winning moves.

b) Indicate a value of S for which Petya cannot win in one move, but for any Petya's move, Vanya can win with his first move. Describe Vanya's winning strategy.

Task 2

Indicate two such values ​​of S for which Petya has a winning strategy, and two conditions are simultaneously satisfied:

− Petya cannot win in one move;

− can win on his second move regardless of how Vanya moves.

For each given value of S, describe Petya's winning strategy.

Task 3

Specify the value of S at which two conditions are simultaneously satisfied:

− Vanya has a winning strategy that allows him to win on the first or second move in any game of Petya;

The district methodologist decided that 20% of the participants should receive an “excellent” rating (an integer, with the decimal part discarded).

To do this, she must determine what score the student had to score in order to get "excellent".

If it is not possible to determine a score such that exactly 20% of the participants get "excellent", fewer participants than 20% should get "excellent".

If there are no such participants (more than 20% of the participants scored the highest score) - these and only these students should receive "excellent".

Write an efficient, memory-efficient program (indicate the version of the programming language you are using, e.g. Borland Pascal 7.0) that should display the lowest score that the participants who got "excellent" scored on the screen. It is known that more than 5 students passed computer science. It is also known that there is a number of points that no participant has received.

At the input of the program, the number of students who passed the exam is first given. Each of the next N lines contains information about students in the format:

where is a string consisting of no more than 30 characters without spaces,

A string of no more than 20 characters without spaces,

An integer in the range from 1 to 99,

An integer in the range from 1 to 100. This data is written with a space, and exactly one between each pair (that is, only three spaces in each line).

Input string example:

Ivanov Ivan 50 87

Sample output:

Solutions to tasks with a detailed answer are not checked automatically.
On the next page, you will be asked to check them yourself.

Finish testing, check answers, see solutions.



RegionCondition 1

(y >= −x*x)

Condition 2

(y >= −x−2)

Condition 3The program will output