oj.uz

Submission #1090046

# Submission time Handle Problem Language Result Execution time Memory
1090046 2024-09-17T16:08:07 Z KALARRY COVID tests (CEOI24_covid) C++14
0 / 100
 7000 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.
    std::vector<bool> find_positive() {
        std::vector<bool> answer(N);
        vector<bool> mask;
        int total_pos = floor(N*P);
        int rem = total_pos;
        for(int i = 0 ; i < N ; i++)
            mask.push_back(false);
        int pos = 0;
        int expect_to_reach = 0;
        double val = (1-P);
        while(val < 0.5)
        {
            expect_to_reach++;
            val *= (1-P);
        }
        while(pos < N)
        {
            int reach = N-1;
            for(int b = expect_to_reach ; b >= 1 ; b/=2)
                while(pos + b <= reach)
                {
                    for(int i = pos ; i <= pos + b ; i++)
                        mask[i] = true;
                    bool res = test_students(mask);
                    for(int i = pos ; i <= pos + b ; i++)
                        mask[i] = false;
                    if(!res)
                    {
                        for(int i = pos ; i <= pos + b ; i++)
                            answer[i] = false;
                        pos += (b+1);
                    }   
                    else
                    {
                        reach = pos + b -1;
                        break;
                    }
                }
            mask[pos] = true;
            bool res = test_students(mask);
            answer[pos] = res;
            mask[pos] = false;
            pos++;
            rem--;
        }
        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:31:14: 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:91:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   91 |         scanf("%d %lf %d", &N, &P, &T);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:107:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  107 |             scanf(" %c", &verdict);
      |             ~~~~~^~~~~~~~~~~~~~~~~

Subtask #0
0.0 / 0.0

# Verdict Execution time Memory Grader output
1 Correct 0 ms 344 KB Output is correct

Subtask #1
0.0 / 10.0

# Verdict Execution time Memory Grader output
1 Execution timed out 7078 ms 344 KB Time limit exceeded
2 Halted 0 ms 0 KB -

Subtask #2
0.0 / 90.0

# Verdict Execution time Memory Grader output
1 Incorrect 2404 ms 344 KB Incorrect
2 Halted 0 ms 0 KB -