oj.uz

Submission #1026691

# Submission time Handle Problem Language Result Execution time Memory
1026691 2024-07-18T09:19:25 Z 김은성(#10945) COVID tests (CEOI24_covid) C++17
0 / 100
 49 ms 344 KB 
#include <cassert>
#include <cstdio>
#include <string>
#include <vector>
#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.
vector<bool> answer, query;
void solve(int lo, int hi){
    int e = (int)(N * P);
    if(lo>hi)
        return;
    int l = lo, h = min(l+e, hi), mid, i;
    while(l < h){
        mid = (l+h)/2;
        for(i=l; i<=mid; i++)
            query[i] = 1;
        if(test_students(query)){
            h = mid;
        }
        else{
            l = mid+1;
        }
        for(i=l; i<=mid; i++)
            query[i] = 0;
    }
    if(h == min(l+e, hi))
        solve(h+1, hi);
    else{
        answer[h] = 1;
        solve(h+1, hi);
    }
}
std::vector<bool> find_positive() {
    answer.resize(N);
    query.resize(N);
    int i;
    for(i=0; i<N; i++)
        answer[i]= query[i] = 0;
    solve(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++) {
        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:31:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:79:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   79 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:95:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   95 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

Subtask #0
0.0 / 0.0

# Verdict Execution time Memory Grader output
1 Incorrect 1 ms 344 KB translate:wrong
2 Halted 0 ms 0 KB -

Subtask #1
0.0 / 10.0

# Verdict Execution time Memory Grader output
1 Incorrect 49 ms 344 KB translate:wrong
2 Halted 0 ms 0 KB -

Subtask #2
0.0 / 90.0

# Verdict Execution time Memory Grader output
1 Incorrect 3 ms 344 KB translate:wrong
2 Halted 0 ms 0 KB -