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Unified State Exam in Computer Science year. Unified State Exam program in computer science - Analysis of problems and materials. Information structuring and information models

With the modern world of technology and the realities of programming, development Unified State Exam in Computer Science has little in common. There are some basic points, but even if you understand a little about the tasks, this does not mean that you will ultimately become a good developer. But there are a great many areas where IT specialists are needed. You can't go wrong if you want to have a stable income above average. In IT you will get it. Provided, of course, that you have the appropriate abilities. And you can develop and grow here as much as you want, because the market is so huge that you can’t even imagine! Moreover, it is not limited only to our state. Work for any company from anywhere in the world! This is all very inspiring, so let preparation for the Unified State Exam in computer science be the first minor step, followed by years of self-development and improvement in this area.

Structure

Part 1 contains 23 short answer questions. This part contains short-answer tasks that require you to independently formulate a sequence of symbols. The assignments test the material of all thematic blocks. 12 tasks belong to the basic level, 10 tasks to an increased level of complexity, 1 task to a high level of complexity.

Part 2 contains 4 tasks, the first of which is of an increased level of complexity, the remaining 3 tasks are of a high level of complexity. The tasks in this part involve writing a detailed answer in free form.

3 hours 55 minutes (235 minutes) are allotted to complete the examination work. It is recommended to spend 1.5 hours (90 minutes) to complete the tasks of Part 1. It is recommended to devote the rest of the time to completing the tasks of part 2.

Explanations for grading assignments

Completion of each task in Part 1 is worth 1 point. Part 1 task is considered completed if the examinee gives an answer that corresponds to the correct answer code. Completion of tasks in part 2 is graded from 0 to 4 points. Answers to tasks in Part 2 are checked and assessed by experts. The maximum number of points that can be obtained for completing tasks in part 2 is 12.

The lesson is devoted to how to solve task 3 of the Unified State Exam in computer science


The 3rd topic is characterized as tasks of a basic level of complexity, completion time - approximately 3 minutes, maximum score - 1

* Some page images are taken from the presentation materials of K. Polyakov

Information structuring and information models

Let us briefly consider the concepts necessary to solve task 3 of the Unified State Exam.

Structuring information- this is the establishment of the main elements in information messages and the establishment of connections between them.

Structuring is done with purpose facilitating the perception and retrieval of information.

Structuring is possible using the following structures (information models):

  • a bunch of:

    • listing of elements collected according to a characteristic feature;

    Vasya, Petya, Kolya 1, 17, 22, 55

    In a set, ordering of elements is not necessary, i.e. The order is not important.

  • linear list

    • The order of the elements is important.

    The tables highlight objects(individual table records) and properties(column names or row names):

  • tree or hierarchy of objects

    • Let's consider family relationships in the tree:

  • "Sons" A: B, C.
  • "Parent" B: A.
  • "Descendants" A: B, C, D, E, F, G.
  • "Ancestors" F: A, C.

    • Root– node without ancestors (A).
    Sheet– a node without children (D, E, F, G).
    Height– the greatest distance from the root to the leaf (number of levels).

  • file system (hierarchy)

    • Let's say there are the following folders (directories) with files on your computer's hard drive:

    We get a tree:

  • graphs

    • Sometimes it is very difficult to structure information using the structures described because of the complex “relationships” between objects. Then you can use the graphs:

    is a set of vertices and connections between them, called edges:

    Graph showing roads between villages

  • matrix and adjacency list

    • is a graph that has a path between any of its vertices.


    Tree is a connected graph without cycles (closed sections).

    Tree is a connected graph without cycles

  • weighted graphs and weight matrix

    • Weighted graphs have an “edge weight”:

    A weight matrix is ​​obtained from weighted graphs, and the inverse transformation is also possible.

    Finding the shortest path (brute force)

    Determining the shortest path between points A and D

    • In USE tasks on this topic, two information models are most often used - tables and diagrams.
    • Information in the table is constructed according to the following rules: at the intersection of a row and a column there is information that characterizes the combination of this row and column.
    • On the diagram information is constructed according to the following rule: if there is a connection between the objects of the diagram, then it is displayed by a line connecting the names of these objects on the diagram.

    Solving tasks 3 of the Unified State Exam in computer science

    3_3: Solution 3 of the Unified State Examination task in computer science (control version No. 1 of the 2018 exam paper, S.S. Krylov, D.M. Ushakov):

    Between settlements A, B, C, D, E, F roads have been built, the length of which is shown in the table (if the cell is empty, there is no road).

    A B C D E F
    A 7 3
    B 7 2 4 1
    C 3 2 7 5 9
    D 4 7 2 3
    E 1 5 2 7
    F 9 3 7

    Determine the length of the shortest path between points A And F .


    ✍ Solution:

    Result: 11

    Video analysis of the task:


    3_4:Solution 3 of the Unified State Examination in computer science (11th version of the State Examination in computer science 2018):

    Roads have been 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 points.

    A B C D E F
    A 3 7 6
    B 3 4 4
    C 7 5 9
    D 4 5 5
    E 6 4 8
    F 9 5 8

    Determine the length shortest path between points A And F provided that you can only travel on the roads indicated in the table.


    ✍ Solution:

    Result: 12


    3_5: Solution 2* of the Unified State Examination in Informatics 2018, option 10 (FIPI, “Unified State Examination Informatics and ICT, standard exam options 2018”, S.S. Krylov, T.E. Churkina):

    Between settlements A, B, C, D, E, F, Z One-way roads have been built. The table shows the length of each road (the absence of a number in the table means that there is no direct road between points).

    A B C D E F Z
    A 3 5 14
    B 2 8
    C 2 7
    D 1 4 4
    E 1 5
    F 12 1 9
    Z

    How many such routes are there from A V Z, which pass through five or more settlements? Items A And Z take into account when calculating. You cannot go through the same checkpoint twice.

    * in the new textbooks, tasks 2 and 3 have been swapped: now 2 is Finding the shortest path, and 3 is Algebra of Logic


    ✍ Solution:

    Result: 6


    3_2: 3 task. Demo version of the Unified State Exam 2018 computer science (FIPI):

    In the figure, the road map of the N-sky district is shown in the form of a graph; the table contains information about the length of each of these roads (in kilometers).

    Since the table and diagram were drawn independently of each other, the numbering of settlements in the table is in no way related to the letter designations on the graph. Determine the length of the road from the point A to point G. In your answer, write down the integer as it is indicated in the table.


    ✍ Solution:
    • Let's count how many edges each vertex has:
    A -> 3 (C D D) B -> 1 (C) C -> 4 (A B D E) D -> 4 (A C D K) D -> 2 (A D) E -> 1 (C ) K -> 1 (G)
  • Only one vertex has three edges - A, so only A can match P3.
  • The vertex also has a unique number of edges D, - two ribs. Top of the table D will correspond P4.
  • Peaks G And IN each have 4 ribs Consider a matrix in which 4 numbers correspond to points P2 And P5.
  • With clause D only the vertex intersects G(G -> 4 (A B D K)). In a weight matrix with vertex D suppressed P5. So it's the top G corresponds P5.
  • IN P5 at the intersection with P3 is the number 6 .

    • Result: 6

    For a detailed solution to this 3rd task from the demo version of the Unified State Exam 2018, watch the video:


    3_1: Unified State Examination in Informatics 2017, assignment from the collection of Ushakova D.M., option 1:

    In the figure, the road map of the N district is shown in the form of a graph; the table contains information about the lengths of these roads (in kilometers).

    Since the table and diagram were drawn independently of each other, the numbering of settlements in the table is in no way related to the letter designations on the graph.
    Determine how long the road from point is D to point TO. In your answer, write down the integer as it is indicated in the table.


    ✍ Solution:
    • Consider the graph and count the number of edges from each vertex:
    A - > 2 ribs (D, B) B - > 4 ribs (A, G, K, D) D - > 4 ribs (A, B, K, D) B - > 2 ribs (D, K) K - > 5 ribs (B, D, C, D, E) E - > 2 ribs (K, D) D -> 3 ribs (B, K, E)
  • We have identified vertices with a unique number of edges: 3 edges correspond to only a vertex D, and 5 edges correspond only to the vertex TO.
  • Let's look at the table and find those rows or columns that have 5 values ​​and 3 values: This is P2 And P4.
  • We get P2 corresponds D, A P4 corresponds TO. At the intersection there is a number 20 .

    • Result: 20

    In addition, you can watch a video of the solution to this Unified State Exam assignment in computer science:


    3_6: Analysis of task 3 of the Unified State Exam option No. 1, 2019 Computer science and ICT Typical exam options (10 options), S.S. Krylov, T.E. Churkina:

    The figure shows a road map of the N-rayon; in the table, an asterisk indicates the presence of a road from one settlement to another; the absence of an asterisk means that there is no such road. Each settlement on the diagram corresponds to its number in the table, but it is not known which number.

    1 2 3 4 5 6 7 8
    1 * * *
    2 * * *
    3 * *
    4 * * * * * *
    5 * * *
    6 * * *
    7 * * *
    8 * * *

    Determine which numbers of settlements in the table can correspond to settlements D And E on the diagram? In your answer, write down these two numbers in ascending order without spaces or punctuation.


    ✍ Solution:
    • First, let's find unique vertices - those that have a unique number of edges: this A(2 ribs) and H(6 ribs). In the table they correspond to numbers 3 and 4:
      • 1 2 A H 5 6 7 8
      1 * * *
      2 * * *
      A * *
      H * * * * * *
      5 * * *
      6 * * *
      7 * * *
      8 * * *
    • According to the diagram, we find that the adjacent vertices for A are B And G. In the table we determine the numbers corresponding to them - 1 and 2. Since according to the assignment they do not interest us, we designate them together:
      • B,G B,G A H 5 6 7 8
      B,G * * *
      B,G * * *
      A * *
      H * * * * * *
      5 * * *
      6 * * *
      7 * * *
      8 * * *
    • Both vertices B and G are adjacent to the already known A and H and, in addition, the vertices F And C. From the first column or first row we find that F or C will correspond to the number 7, and from the second line to the number 8. Let us designate them in the table:
      • B,G B,G A H 5 6 F,C F,C
      B,G * * *
      B,G * * *
      A * *
      H * * * * * *
      5 * * *
      6 * * *
      F,C * * *
      F,C * * *
    • As a result, we obtain that the required vertices are D And E- numbers correspond 5 And 6 . Since it does not matter which digit this or that vertex should correspond to, in the answer we will simply write these digits in ascending order.

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