Submission #1060747

#	Time	Username	Problem	Language	Result	Execution time	Memory
1060747		Dan4Life	COVID tests (CEOI24_covid)	C++17	27.45 / 100	2339 ms	344 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) begin(a), end(a)
using ll = long long;
using vi = vector<int>;
using ar2 = array<int,2>;
using ar3 = array<int,3>;
using ar4 = array<int,4>;
const int INF = (int)2e9;
const int mxN = (int)1e6+10;
 
int N;
double P;
map<vector<bool>,bool> M;
// 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);
	//if(M.count(mask)) return M[mask];
    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.
vector<bool> find_positive() {
    vector<bool> answer(N,false), test(N,false);
    vector<int> XD(N,0); iota(all(XD),0); random_shuffle(all(XD));
    if(P>0.08){
		int likely = P*1000*1.8;
		for(int i = 0; i < N; i++){
			if(!likely) break;
			test[XD[i]]=1;
			if(test_students(test))
				answer[XD[i]]=1, likely--;
			test[XD[i]]=0;
		}
		return answer;
	}
	int l = 0;
	while(l<N){
		for(int i = 0; i < N; i++) test[XD[i]]=0;
		for(int i = l; i < N; i++) test[XD[i]]=1;
		if(!test_students(test)) return answer;
		for(int i = 0; i < N; i++) test[XD[i]]=0;
		int r = N-1, oldL = l;
		while(l<r){
			int mid = (l+r)/2;
			for(int i = oldL; i<=mid; i++) test[XD[i]]=1;
			if(test_students(test)) r=mid;
			else l=mid+1;
			for(int i = oldL; i<=mid; i++) test[XD[i]]=0;
		}
		answer[XD[l]]=1; l++;
	}
    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:32:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   32 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:77:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   77 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:93:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   93 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 17.450000001 / 90