Submission #1052753

#	Time	Username	Problem	Language	Result	Execution time	Memory
1052753		beaconmc	COVID tests (CEOI24_covid)	C++14	60.21 / 100	1481 ms	704 KiB

Main

    #include <cassert>
    #include <cstdio>
    #include <string>
    #include <vector>
    #include <bits/stdc++.h>
     
    typedef long long ll;
    #define FOR(i,x,y) for(ll i=x; i<y; i++)
    #define FORNEG(i,x,y) for(ll i=x; i>y; i--)
     
    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';
    }
     
     
    vector<ll> dp(ll a, ll b, bool result){
        //cout << a << " " << b << " " << result << endl;
        if (result == 0) return {};
        if (a==b){
            if (result == 1) return {a};
            else return {};
        }
        ll mid = (a+b)/2;
        vector<ll> temp, temp2;
        vector<bool> test(N), test2(N);
        FOR(i,a,mid+1) test[i] = 1;
        FOR(i,mid+1,b+1) test2[i] = 1;
     
        if (rand()%2==0){
            ll result1 = test_students(test);
            temp = dp(a, mid, result1);
            ll result2 = -1;
            if (result1==0) result2 = 1;
            else result2 = test_students(test2);
            temp2 = dp(mid+1, b, result2);
        }else{
            ll result2 = test_students(test2);
            ll result1 = -1;
            temp2 = dp(mid+1, b, result2);
            
            if (result2==0) result1 = 1;
            else result1 = test_students(test);
            temp = dp(a, mid, result1);
            
        }
     
        
        vector<ll> ans;
        for (auto&i : temp) ans.push_back(i);
        for (auto&i : temp2) ans.push_back(i);
        return ans;
    }
     
    std::vector<bool> find_positive() {
        std::vector<bool> answer(N);
        vector<ll> stuff;
        vector<ll> temp;
        ll c;
        if (P==0.2) c = 4;
        else if (P==0.158765) c = 4;
        else if (P == 0.104571 ) c = 8;
        else if (P == 0.068648 ) c = 8;
        else if (P==0.039856 ) c = 8;
        else if (P == 0.028545 ) c = 32; 
        else if (P==0.011546) c = 32;
        else c = 1000;
        //cout << c << endl;
        FOR(i,0,(N-1)/c + 1){
            ll a = c*i;
            ll b = min(c*(i+1)-1, (ll)N-1);
     
            vector<bool> test(N);
            FOR(j,a,b+1) test[j] = 1;
            temp = dp(a, b, test_students(test));
            for (auto&k : temp) stuff.push_back(k);
     
        }
        
        FOR(i,0,N) answer[i] = 0;
        for (auto&i : stuff) answer[i] = 1;
     
        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 'bool test_students(std::vector<bool>)':
Main.cpp:35:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |         scanf(" %c", &answer);
      |         ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:111:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |         scanf("%d %lf %d", &N, &P, &T);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:127:18: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  127 |             scanf(" %c", &verdict);
      |             ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 50.210000001 / 90