Submission #1090565

#	Time	Username	Problem	Language	Result	Execution time	Memory
1090565		lucri	COVID tests (CEOI24_covid)	C++17	100 / 100	1892 ms	344 KiB

Main

#include <bits/stdc++.h>
/// You may use:

// The number of students
int N,T;

// 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> answer;
std::vector<bool> test;
std::vector<int> ind;
int p[5010];
std::vector<int>ns;
void calculeaza(int b,int e)
{
    if(b>e)
        return;
    int ce=e;
    b=0;
    while(b+1!=e)
    {
        int mid=(b+e)/2;
        for(int i=b+1;i<=mid;++i)
            test[p[i]]=1;
        bool r=test_students(test);
        for(int i=b+1;i<=mid;++i)
            test[p[i]]=0;
        if(r==false)
            b=mid;
        else
            e=mid;
    }
    answer[p[e]]=1;
    std::reverse(ns.begin(),ns.end());
    for(int i=e+1;i<=ce;++i)
        ns.push_back(p[i]);
    std::reverse(ns.begin(),ns.end());
}
void raspunde(int sz,int sz2)
{
    for(int i=0;i<N;++i)
        ns.push_back(ind[i]);
    while(ns.size())
    {
        int x=ns.size();
        if(rand()%2==1)
            x=std::min(x,sz);
        else
            x=std::min(x,sz2);
        p[0]=0;
        while(x--)
        {
            p[++p[0]]=ns.back();
            ns.pop_back();
        }
        for(int i=1;i<=p[0];++i)
            test[p[i]]=1;
        bool r=test_students(test);
        for(int i=1;i<=p[0];++i)
            test[p[i]]=0;
        if(r==true)
            calculeaza(1,p[0]);
    }
}
std::vector<bool> find_positive()
{
    for(int i=0;i<N;++i)
    {
        answer[i]=test[i]=0;
        ind[i]=i;
    }
    random_shuffle(ind.begin(),ind.end());
    if(T==1)//subtask 1
    {
        raspunde(1,1);
    }
    else if(P>0.17)///P=0.2
    {
        raspunde(3,3);
    }
    else if(P>0.11)///P=0.158765
    {
        raspunde(4,4);
    }
    else if(P>0.1)//P=0.104571
    {
        raspunde(7,7);
    }
    else if(P>0.06)///P=0.068648
    {
        raspunde(8,8);
    }
    else if(P>0.03)///P=0.039856
    {
        raspunde(15,15);
    }
    else if(P>0.02)///P=0.028545
    {
        raspunde(24,24);
    }
    else if(P>0.01)///P=0.011546
    {
        raspunde(58,58);
    }
    else if(P>0.005)///P=0.005256
    {
        raspunde(200,200);
    }
    else///P=0.001
    {
        raspunde(500,500);
    }
    return answer;
}

int main() {
    scanf("%d %lf %d", &N, &P, &T);

    // You may perform any extra initialization here.
    srand(time(0));
    answer.resize(N);
    ind.resize(N);
    test.resize(N);
    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:25:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   25 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:143:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  143 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:162:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  162 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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