oj.uz

Submission #1068617

# Submission time Handle Problem Language Result Execution time Memory
1068617 2024-08-21T10:58:11 Z vjudge1 COVID tests (CEOI24_covid) C++17
10 / 100
 33 ms 344 KB 
#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.
int T;
std::vector<bool> find_positive() {
    std::vector<bool> answer(N);

    if (T == 1) {
        for (int i = 0; i < N; i++) {
            vector<bool> query(N);
            query[i] = 1;
            if (test_students(query))
                answer[i] = 1;
        }
        return answer;
    }

    int last = -1;
    vector<bool> query(N);
    for (int i = 0; i < N; i++) {
        int l = last + 1, r = N, ans = -1;
        while (l < r) {
            int mid = (l + r) / 2;
            
            fill(query.begin() + last + 1, query.begin() + mid + 1, true);
            if (test_students(query))
                ans = mid, r = mid;
            else
                l = mid + 1;
        }
        if (ans == -1)
            break;
        answer[ans] = true;
        last = ans;
    }

    return answer;
}

int main() {
    
    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: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:76:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:92:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |         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
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 10 ms 344 KB Output is correct
2 Correct 12 ms 344 KB Output is correct
3 Correct 9 ms 344 KB Output is correct
4 Correct 8 ms 344 KB Output is correct
5 Correct 8 ms 344 KB Output is correct
6 Correct 8 ms 344 KB Output is correct
7 Correct 6 ms 344 KB Output is correct
8 Correct 6 ms 344 KB Output is correct
9 Correct 7 ms 344 KB Output is correct
10 Correct 6 ms 344 KB Output is correct
11 Correct 6 ms 344 KB Output is correct
12 Correct 6 ms 344 KB Output is correct
13 Correct 6 ms 344 KB Output is correct
14 Correct 6 ms 344 KB Output is correct
15 Correct 6 ms 344 KB Output is correct
16 Correct 6 ms 344 KB Output is correct
17 Correct 6 ms 344 KB Output is correct

Subtask #2
0.0 / 90.0

# Verdict Execution time Memory Grader output
1 Incorrect 33 ms 344 KB translate:wrong
2 Halted 0 ms 0 KB -