oj.uz

Submission #1076789

# Submission time Handle Problem Language Result Execution time Memory
1076789 2024-08-26T16:33:02 Z raphaelp COVID tests (CEOI24_covid) C++14
64.16 / 100
 2121 ms 596 KB 
#include <bits/stdc++.h>
using namespace std;

/// You may use:

// The number of students
int N;

// The probability any given student is positive
double P;

// This function performs a test on a subset of samples.
// Its argument is a vector of Booleans of length N,
// where the i-th element is true if the i-th sample should be added to the mix.
// It returns true if (and only if) at least one of the samples in the mix is positive.
bool test_students(std::vector<bool> mask)
{
    assert(mask.size() == (size_t)N);

    std::string mask_str(N, ' ');
    for (int i = 0; i < N; i++)
        mask_str[i] = mask[i] ? '1' : '0';

    printf("Q %s\n", mask_str.c_str());
    fflush(stdout);

    char answer;
    scanf(" %c", &answer);
    return answer == 'P';
}

/// You should implement:

// This function will be called once for each test instance.
// It should use test_students to determine which samples are positive.
// It must return a vector of Booleans of length N,
// where the i-th element is true if and only if the i-th sample is positive.
void rectest(int L, int R, vector<bool> &test, vector<bool> &answer)
{
    if (test_students(test) == 0)
        return;
    if (L == R)
    {
        answer[L] = 1;
        return;
    }
    int m = (L + R) / 2;
    for (int i = L; i <= m; i++)
        test[i] = 0;
    rectest(m + 1, R, test, answer);
    for (int i = L; i <= m; i++)
        test[i] = 1;
    for (int i = m + 1; i <= R; i++)
        test[i] = 0;
    rectest(L, m, test, answer);
}
std::vector<bool> find_positive()
{
    std::vector<bool> answer(N);
    vector<bool> left(N, 0);
    int div = ceil((double)1 / P);
    div /= 2;
    div = max(div, 4);
    vector<bool> test(N, 0);
    int L = 0, R = div - 1;
    if (P > 0.2)
    {
        test.assign(N, 1);
        rectest(0, N - 1, test, answer);
        return answer;
    }
    while (true)
    {
        R = min(R, N - 1);
        L = min(L, N - 1);
        for (int i = L; i <= R; i++)
            left[i] = 1;
        while (test_students(left))
        {
            int L2 = L, R2 = R;
            while (L2 < R2)
            {
                int m = (L2 + R2) / 2;
                for (int i = L2; i <= m; i++)
                    test[i] = (1 & left[i]);
                bool b = test_students(test);
                for (int i = L2; i <= m; i++)
                    test[i] = 0;
                if (b)
                    R2 = m;
                else
                    L2 = m + 1;
            }
            answer[L2] = 1;
            left[L2] = 0;
        }
        for (int i = L; i <= R; i++)
            left[i] = 0;
        if (R == N - 1)
            break;
        L += div, R += div;
    }
    return answer;
}

int main()
{
    int T;
    scanf("%d %lf %d", &N, &P, &T);

    // You may perform any extra initialization here.

    for (int i = 0; i < T; i++)
    {
        std::vector<bool> answer = find_positive();
        assert(answer.size() == (size_t)N);

        std::string answer_str(N, ' ');
        for (int j = 0; j < N; j++)
            answer_str[j] = answer[j] ? '1' : '0';

        printf("A %s\n", answer_str.c_str());
        fflush(stdout);

        char verdict;
        scanf(" %c", &verdict);
        if (verdict == 'W')
            exit(0);
    }

    return 0;
}

Compilation message

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:28:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:109:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  109 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:126:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  126 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #0
0.0 / 0.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 344 KB Output is correct

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 344 KB Output is correct
2 Correct 18 ms 344 KB Output is correct
3 Correct 15 ms 344 KB Output is correct
4 Correct 18 ms 344 KB Output is correct
5 Correct 13 ms 344 KB Output is correct
6 Correct 15 ms 344 KB Output is correct
7 Correct 12 ms 344 KB Output is correct
8 Correct 13 ms 344 KB Output is correct
9 Correct 14 ms 344 KB Output is correct
10 Correct 6 ms 344 KB Output is correct
11 Correct 14 ms 596 KB Output is correct
12 Correct 9 ms 344 KB Output is correct
13 Correct 10 ms 344 KB Output is correct
14 Correct 15 ms 344 KB Output is correct
15 Correct 15 ms 344 KB Output is correct
16 Correct 12 ms 344 KB Output is correct
17 Correct 2 ms 344 KB Output is correct

Subtask #2
54.160000002 / 90.0

# Verdict Execution time Memory Grader output
1 Correct 31 ms 344 KB Output is correct (P=0.001, F=15.1, Q=11.1) -> 90.00 points
2 Correct 117 ms 508 KB Output is correct (P=0.005256, F=51.1, Q=49.5) -> 90.00 points
3 Correct 252 ms 344 KB Output is correct (P=0.011546, F=94.9, Q=98.1) -> 79.30 points
4 Correct 522 ms 344 KB Output is correct (P=0.028545, F=191.5, Q=204.5) -> 70.78 points
5 Correct 672 ms 596 KB Output is correct (P=0.039856, F=246.3, Q=268.3) -> 66.31 points
6 Correct 1018 ms 344 KB Output is correct (P=0.068648, F=366.2, Q=409.5) -> 61.10 points
7 Correct 1352 ms 344 KB Output is correct (P=0.104571, F=490.3, Q=556.8) -> 58.35 points
8 Correct 1793 ms 344 KB Output is correct (P=0.158765, F=639.1, Q=723.0) -> 59.01 points
9 Correct 2121 ms 344 KB Output is correct (P=0.2, F=731.4, Q=852.4) -> 54.16 points