Submission #1076866

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076866		abouton	COVID tests (CEOI24_covid)	C++17	16.95 / 100	2571 ms	596 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 = 3;
    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';
    }
    void tester(int a, int b)
    {
        //printf("%d %d\n", a, b);
        if (b <= a) return;
        if (b==a+1)
        {
            vector<bool> quest(N);
            quest[a] = true;
            answer[a] = test_students(quest);
            return;
        }
        vector<bool> quest(N);
        for (int i = a; i < b; i ++) quest[i] = true;
        if (!test_students(quest)) return; 
        int t = (b-a)/K;
        int r = (b-a)%K;
        int nbit = 0, cur = a;
        while (cur < b)
        {
            int deb = cur;
            cur += t;
            cur += (nbit<r);
            nbit++;
            //printf("%d a %d\n", deb, cur);
            tester(deb, cur);
        }
    }
     
    /// 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() {
        if (P<0.01 || P > 0.12)
        {
        answer.clear();
        answer.resize(N);
        tester(0,N);
        }
        else
        {
        answer.clear();
    answer.resize(N);
    for (int i = 0; i < N; i ++) answer[i] = true;
    int taille;
    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;
        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:76:9: warning: unused variable 'taille' [-Wunused-variable]
   76 |     int taille;
      |         ^~~~~~
Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:27:14: 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:104:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |         scanf("%d %lf %d", &N, &P, &T);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:120:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  120 |             scanf(" %c", &verdict);
      |             ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 6.949999998 / 90