Submission #1076793

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076793		oscar1f	COVID tests (CEOI24_covid)	C++17	55.55 / 100	2728 ms	600 KiB

Main

#include<bits/stdc++.h>
#include <cassert>
#include <cstdio>
#include <string>
#include <vector>
using namespace std;

/// You may use:

// The number of students
int N,nbTest;
vector<bool> rep;
vector<bool> attendu;

// 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(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';
}

/*bool test_students(vector<bool> mask) {
    nbTest++;
    bool ans=false;
    for (int i=0;i<N;i++) {
        if (mask[i] and attendu[i]) {
            ans=true;
        }
    }
    return ans;
}*/

bool dicho(int deb,int fin,bool assure) {
    bool ans;
    if (!assure) {
        vector<bool> quest;
        for (int i=0;i<N;i++) {
            if (i>=deb and i<=fin) {
                quest.push_back(true);
            }
            else {
                quest.push_back(false);
            }
        }
        ans=test_students(quest);
    }
    else {
        ans=true;
    }
    if (ans) {
        if (deb==fin) {
            rep[deb]=true; 
        }
        else {
            int mid;
            if (P>0.01) {
                mid=(3*deb+fin)/4;
            }
            else {
                mid=(deb+fin)/2;
            }
            if (dicho(deb,mid,false)) {
                dicho(mid+1,fin,false);
            }
            else {
                dicho(mid+1,fin,true);
            }
        }

    }
    return ans;
}

/// 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() {
    vector<bool> quest(N,true);
    rep.clear();
    rep.resize(N,false);
    dicho(0,N-1,false);
    return rep;
}

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;
}

/*int main() {
    int T;
    cin>>N>>P>>T;

    // You may perform any extra initialization here.
    char val;
    for (int i = 0; i < T; i++) {
        attendu.clear();
        for (int j=0;j<N;j++) {
            cin>>val;
            //cout<<val;
            attendu.push_back(val=='1');
        }
        std::vector<bool> answer = find_positive();
        for (int j=0;j<N;j++) {
            if (attendu[j]!=answer[j]) {
                cout<<"PROBLEME"<<" "<<i<<" "<<j<<endl;
                return 0;
            }
        }
    }
    cout<<nbTest/T<<endl;
    cout<<"OK"<<endl;
    return 0;
}*/

Compilation message (stderr)

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:33:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   33 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:105:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  105 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:121:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  121 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 45.54999999899999 / 90