Submission #1119869

#	Time	Username	Problem	Language	Result	Execution time	Memory
1119869		Tenis0206	COVID tests (CEOI24_covid)	C++11	0 / 100	1674 ms	336 KiB

Main

#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.

std::vector<bool> answer;

bool my_test_students(int st, int dr)
{
    vector<bool> mask(N);
    for(int i=st;i<=dr;i++)
    {
        mask[i] = true;
    }
    return test_students(mask);
}

void divide(int st, int dr)
{
    if(st == dr)
    {
        answer[st] = true;
        return;
    }
    int mij = (st + dr) >> 1;
    bool ok_st = my_test_students(st, mij);
    bool ok_dr = my_test_students(mij + 1, dr);
    if(ok_st)
    {
        divide(st, mij);
    }
    if(ok_dr)
    {
        divide(mij + 1, dr);
    }
}

void find_positive() {

    if(P < 0.03)
    {
        divide(0, N-1);
    }
    else
    {
        vector<bool> mask(N);
        for(int i=0;i<N;i++)
        {
            mask[i] = false;
        }
        /*for(int i=0;i<N;i++)
        {
            mask[i] = true;
            bool ok = test_students(mask);
            answer[i] = ok;
            mask[i] = false;
        }
        */
    }
}

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++) {
        answer.resize(N);
        for(int j=0;j<N;j++)
        {
            answer[j] = false;
        }
        find_positive();

        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 (stderr)

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:97:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   97 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:117:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  117 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 0 / 10
• Subtask 2: 0 / 90