Submission #1175612

#	Time	Username	Problem	Language	Result	Execution time	Memory
1175612		MuhammadSaram	COVID tests (CEOI24_covid)	C++20	56.97 / 100	574 ms	432 KiB

Main

#include <bits/stdc++.h>

using namespace std;

int N;

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(string mask_str) {
    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.
vector<bool> find_positive() {
    vector<bool> ans(N);
    int C;
    if (P==0.001)
    {
    	string s(N,'1');
    	if (!test_students(s))
    		return ans;
    }
    if (P<=0.01)
    	C=1;
    else if(P<=0.02)
    	C=3;
    else if(P<=0.06)
    	C=9;
    else if(P<=0.1)
    	C=15;
    else if(P<=0.15)
    	C=36;
    else
    	C=60;
    vector<int> v[C];
    for (int i=0;i<N;i++)
    	v[i%C].push_back(i);
    for (int j=0;j<C;j++)
    {
    	int pre=-1;
    	while (1)
    	{
    		int s=pre,e=v[j].size();
    		while (s+1<e)
    		{
    			int mid=(s+e)/2;
    			string q(N,'0');
    			for (int i=s+1;i<=mid;i++)
    				q[v[j][i]]='1';
    			bool b=test_students(q);
    			if (b)
    				e=mid;
    			else
    				s=mid;
    		}
    		if (e<v[j].size())
    			ans[v[j][e]]=1;
    		else
    			break;
    		pre=e;
    	}
    }

    return ans;
}

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::string)':
Main.cpp:17:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   17 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:82:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   82 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:98:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 0 / 10
• Subtask 2: 56.97 / 90