Submission #1076855

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076855		abouton	COVID tests (CEOI24_covid)	C++17	10 / 100	743 ms	344 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;
int K = 2;
vector<bool> answer;

// 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);
    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> find_positive() {
    answer.clear();
    answer.resize(N);
    for (int i = 0; i < N; i ++) answer[i] = true;
    int taille;
    if (P >= 0.3) taille = 1;
    else taille = ceil(log(0.8)/log(1-P));
    for (int x = 0; x < 50; x ++)
    {
    vector<bool> quest(N);
    for (int i =0; i < N; i ++)
    {
        int rep = (rand()%30 == 0);
        if (rep) quest[i] = true;
    }
    if (!test_students(quest)) for (int i = 0; i < N; i ++) if (quest[i]) answer[i] = 0;
    }
    vector<bool> truc(N);
    for (int i = 0; i < N; i ++) truc[i] = 0;
    for (int i = 0; i < N; i ++)
    {
        if (answer[i])
        {
            truc[i] = 1;
            if (!test_students(truc)) answer[i] = 0;
            truc[i] = 0;
        }
    }
    return answer;
}

int main() {
    int T;
    srand(time(NULL));
    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 (stderr)

Main.cpp: In function 'std::vector<bool> find_positive()':
Main.cpp:41:9: warning: variable 'taille' set but not used [-Wunused-but-set-variable]
   41 |     int taille;
      |         ^~~~~~
Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:27:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:71:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   71 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:86:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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