Submission #1137592

#	Time	Username	Problem	Language	Result	Execution time	Memory
1137592		Muhammad_Aneeq	COVID tests (CEOI24_covid)	C++20	0 / 100	7037 ms	99468 KiB

Main

#include <cassert>
#include <cstdio>
#include <string>
#include <vector>
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(vector<bool> mask) {
    assert(mask.size() == (size_t)N);

    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';
}
vector<bool>vals;
vector<bool> answer;
bool ask(int l,int r)
{
    for (int i=l;i<=r;i++)
        vals[i]=1;
    int f=test_students(vals);
    for (int i=l;i<=r;i++)
        vals[i]=0;
    return f;
}
void divi(int l,int r)
{
    int mid=(l+r)/2;
    if (l==r)
    {
        answer[l]=1;
        return;
    }
    if (ask(l,mid))
        divi(l,r);
    if (ask(mid+1,r))
        divi(mid+1,r);
}
vector<bool> find_positive() 
{
    vals.resize(N);
    answer=vals;
    divi(0,N-1);
    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++) {
        vector<bool> answer = find_positive();
        assert(answer.size() == (size_t)N);

        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:29:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:66:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   66 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:82:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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