Submission #1061450

#	Time	Username	Problem	Language	Result	Execution time	Memory
1061450		Dan4Life	COVID tests (CEOI24_covid)	C++17	100 / 100	1735 ms	596 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;
 
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');
}

bool test(int l, int r){
    vector<bool> testt(N,0);
    for(int i = l; i <= r; i++) testt[i]=1;
    return test_students(testt);
}
 
vector<bool> find_positive() {
    vector<bool> answer(N,0);
    if(!P) return answer;
    if(P>=0.3){
        for(int i = 0; i < N; i++)
            answer[i]=test(i,i);
        return answer;
    } 
    int B = 0; double prob = 1.0-P;
    while(prob>=0.5) prob*=(1.0-P), B++;
    if(P>0.16) B=3;
    else if(P>0.1 and P<0.15) B=7;
    for(int i = 0; i < N; i+=B){
        int rr = min(N,i+B)-1;
        while(i<=rr and test(i,rr)){
            int l = i, r = rr;
            while(l<r){
                int mid = (l+r-1)/2;
                if(test(l,mid)) r=mid;
                else l=mid+1;
            }
            answer[l]=1; i=l+1,rr=min(N-1,l+B);
        }
    }
    return answer;
}
 
int main() {
    int T;
    scanf("%d %lf %d", &N, &P, &T);
 
    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:26:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:65:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:79:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   79 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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