Submission #1076849

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
1076849	2024-08-26T17:18:21 Z	raphaelp	COVID tests (CEOI24_covid)	C++14	Compilation error	0 ms	0 KB

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.
void rectest(int L, int R, vector<bool> &test, vector<bool> &answer)
{
    if (test_students(test) == 0)
        return;
    if (L == R)
    {
        answer[L] = 1;
        return;
    }
    int m = (L + R) / 2;
    for (int i = L; i <= m; i++)
        test[i] = 0;
    rectest(m + 1, R, test, answer);
    for (int i = L; i <= m; i++)
        test[i] = 1;
    for (int i = m + 1; i <= R; i++)
        test[i] = 0;
    rectest(L, m, test, answer);
}
std::vector<bool> find_positive()
{
    std::vector<bool> answer(N);
    vector<bool> left(N);
    int div = 1000;
    if (P < 0.1)
        div = ceil((double)1 / P);
    if (P == 0.2)
        div = 4;
    if (P == 0.158765)
        div = 5;
    if (P == 0.104571)
        div = 6;
    vector<bool> test(N, 0);
    int L = 0, R = div - 1;
    if (P > 0.2)
    {
        test.assign(N, 1);
        rectest(0, N - 1, test, answer);
        return answer;
    }
    int L = 0, R = 1;
    test[0] = 1;
    while (L != N)
    {
        while (L + div > R && R < N)
        {
            test[R] = 1;
            R++;
        }
        if (test_students(test))
        {
            int L2 = L, R2 = R;
            while (L2 != R2)
            {
                int m = (L2 + R2) / 2;
                for (int i = L2; i <= m; i++)
                    left[i] = 1;
                bool b = test_students(left);
                for (int i = L2; i <= m; i++)
                    left[i] = 0;
                if (b)
                    R2 = m;
                else
                    L2 = m + 1;
            }
            answer[L2] = 1;
            while (L < L2)
            {
                test[L] = 0;
                L++;
            }
        }
        else
        {
            while (L < R)
            {
                test[L] = 0;
                L++;
            }
        }
    }
    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 'std::vector<bool> find_positive()':
Main.cpp:78:9: error: redeclaration of 'int L'
   78 |     int L = 0, R = 1;
      |         ^
Main.cpp:71:9: note: 'int L' previously declared here
   71 |     int L = 0, R = div - 1;
      |         ^
Main.cpp:78:16: error: redeclaration of 'int R'
   78 |     int L = 0, R = 1;
      |                ^
Main.cpp:71:16: note: 'int R' previously declared here
   71 |     int L = 0, R = div - 1;
      |                ^
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:125:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  125 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:142:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  142 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~