Submission #1254483

#	Time	Username	Problem	Language	Result	Execution time	Memory
1254483		ofoz	COVID tests (CEOI24_covid)	C++20	42.38 / 100	970 ms	408 KiB

Main

#include <bits/stdc++.h>
#pragma GCC optimize("O2") 
using namespace std;
#define vi vector<int>
#define pi pair<int, int>
#define ppi pair<pair<int, int>, int>
#define mtis multiset<pi>
#define endl '\n'

/// 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';
}
bool query_range(int l, int r) {
    vector<bool> cur(N);
    for (int i = l; i <= r; i++) cur[i] = 1;
    return test_students(cur);
}

void search(int l, int r, vector<bool>& answer, int& amount, bool hasPos = 0) {
    if (!hasPos) {
        if (l == r) {
            if (query_range(l, r)) answer[l] = 1;
            amount--;
            return;
        }
        int m = (l+r)/2;
        bool b1 = query_range(l, m), b2 = query_range(m+1, r);
        if (b1) search(l, m, answer, amount, 1);
        if (!amount) return;
        if (b2) search(m+1, r, answer, amount, 1);
        return;
    }
    if (l == r) { answer[l] = 1; amount--; }
    else {
        int m = (l+r)/2;
        bool b1 = query_range(l, m), b2;
        if (!b1) { search(m+1, r, answer, amount, 1); return; }
        b2 = query_range(m+1, r);
        if (b1) search(l, m, answer, amount, 1);
        if (!amount) return;
        if (b2) search(m+1, r, answer, amount, 1);
    }
}
// 010001
vector<bool> find_positive() {
    vector<bool> answer(N, 0);
    int amount;
    if (P == 0.001f) amount = 50;
    else if (P - 0.005256f <= 0.001f) amount = 100;
    else if (P - 0.011546f <= 0.001f) amount = 100;
    else if (P - 0.028545f <= 0.001f) amount = 200;
    else if (P - 0.039856f <= 0.001f) amount = 230;
    else if (P - 0.068648f <= 0.001f) amount = 250;
    else if (P - 0.104571f <= 0.001f) amount = 340;
    else if (P - 0.158765f <= 0.001f) amount = 450;
    else if (P - 0.2f <= 0.001f) amount = 600;
    else assert(false);
    search(0, N-1, answer, amount);
    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;
}

// bool test_students(std::vector<bool> mask)

Compilation message (stderr)

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:33:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:87:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   87 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:103:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  103 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 0 / 10
• Subtask 2: 42.38 / 90