Subtasks

The concept of subtasks was first formally introduced in IOI 2010. The idea is basically to split a problem into two or more smaller problems with gradually increasing difficulty, and assign them different points.

For example:

Subtask 1 (20 points)

- N = 1

- 1 ≤ K ≤ 100

Subtask 2 (20 points)

- 1 ≤ N ≤ 100

- K = 1

Subtask 3 (60 points)

- 1 ≤ N ≤ 100

- 1 ≤ K ≤ 100

In this type type of problem, you won’t be writing a Constraints() method. Instead, you will be writing SubtaskX() methods, where X is the subtask number.

Note

As of this version, you can define up to 10 subtasks: Subtask1() .. Subtask10().

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Subtask definitions

A subtask is basically just a set of constraints. It can be specified by the method SubtaskX(), where X is the subtask number. Inside the method, the constraint specifications are given, similar to what you usually do in the Constraints() method.

Thus, the above example can be implemented as:

void Subtask1() {
    CONS(N == 1);
    CONS(1 <= K && K <= 100);
}

void Subtask2() {
    CONS(1 <= N && N <= 100);
    CONS(K == 1);
}

void Subtask3() {
    CONS(1 <= N && N <= 100);
    CONS(1 <= K && K <= 100);
}

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Test groups

If your problem has subtasks, you will be writing test groups, not test cases. Refer to this chapter on how to do that.

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Notes

Currently, tcframe does not provide a way to specify subtask points. It is up to the grader to implement the scoring.