Submission #1231135

#	Time	Username	Problem	Language	Result	Execution time	Memory
1231135		PVM_pvm	COVID tests (CEOI24_covid)	C++20	46.24 / 100	856 ms	408 KiB

Main

#include<bits/stdc++.h>
using namespace std;
#define MAXN 1007

/// 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(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';
}

/// 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.
bool otgov[MAXN];
void findd(int l, int r)
{
    vector<bool> nl(N,0);
    for (int q=l;q<=r;q++) nl[q]=1;
    bool otg=test_students(nl);
    if (otg)
    {
        if (l==r)
        {
            otgov[l]=1;
            return;
        }
        int mid=(l+r)/2;
        findd(l,mid);
        findd(mid+1,r);
    }
}
vector<bool> find_positive() {
    if (false)
    {
        vector<bool> answer(N);
        for (int q=0;q<N;q++) otgov[q]=0;
        findd(0,N/2-1);
        findd(N/2,N-1);
        for (int q=0;q<N;q++) answer[q]=otgov[q];
        return answer;
    }
    else if (P>0.02)
    {
        vector<bool> answer(N,0);
        for (int cq=0;cq<N;cq+=8)
        {
            vector<bool> nl3(N,0);
            for (int w=cq;w<cq+8;w++) nl3[w]=1;
            bool toi=test_students(nl3);
            if (!toi) continue;
            int lr=cq,rr=cq+7;
            while (true)
            {
                vector<bool> nl(N,0);
                for (int q=lr;q<=rr;q++) nl[q]=1;
                bool otg;
                if (rr-lr+1!=8 ) otg=test_students(nl);
                else otg=1;
                if (otg==0) break;
                int l=lr-1,r=rr;
                while (l<r-1)
                {
                    int mid=(l+r)/2;
                    vector<bool> nl2(N,0);
                    for (int q=lr;q<=mid;q++) nl2[q]=1;
                    otg=test_students(nl2);
                    if (otg) r=mid;
                    else l=mid;
                }
                answer[r]=1;
                lr=r+1;
            }
        }
        return answer;
    }
    else
    {
        vector<bool> answer(N,0);
        int lr=0,rr=N;
        while (true)
        {
            vector<bool> nl(N,0);
            for (int q=lr;q<=rr;q++) nl[q]=1;
            bool otg=test_students(nl);
            if (otg==0) break;
            int l=lr-1,r=rr;
            while (l<r-1)
            {
                int mid=(l+r)/2;
                vector<bool> nl2(N,0);
                for (int q=lr;q<=mid;q++) nl2[q]=1;
                otg=test_students(nl2);
                if (otg) r=mid;
                else l=mid;
            }
            answer[r]=1;
            lr=r+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++) {
        vector<bool> answer = find_positive();
        assert(answer.size() == (size_t)N);

        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: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:129:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  129 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:145:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  145 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 0 / 10
• Subtask 2: 46.24 / 90