Submission #1033728

#	Time	Username	Problem	Language	Result	Execution time	Memory
1033728		ainta	COVID tests (CEOI24_covid)	C++17	10 / 100	19 ms	344 KiB

Main

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

#define rng(i,a,b) for(int i=int(a);i<=int(b);i++)
#define rep(i,b) rng(i,0,b-1)
#define gnr(i,b,a) for(int i=int(b);i>=int(a);i--)
#define per(i,b) gnr(i,b-1,0)
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define bg begin()
#define ed end()
#define all(x) x.bg,x.ed
#define si(x) int(x.size())
template<class t> using vc=vector<t>;
template<class t> using vvc=vc<vc<t>>;
typedef long long ll;
using pii=pair<int,int>;
using vi=vc<int>;
using uint=unsigned;
using ull=unsigned long long;
using pil=pair<int,ll>;
using pli=pair<ll,int>;
using pll=pair<ll,ll>;
using t3=tuple<int,int,int>;

#include <cassert>
#include <cstdio>
#include <string>
#include <vector>

/// 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(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, mask;
void Go(int b, int e){
	rep(i,N)mask[i]=0;
	rng(i,b,e)mask[i]=1;
	if(test_students(mask)){
		if(b==e)answer[b]=1;
		else{
			Go(b,(b+e)/2);
			Go((b+e)/2+1,e);
		}
	}
}
std::vector<bool> find_positive() {
	answer.resize(N);
	mask.resize(N);
	Go(0,N/2-1);
	Go(N/2,N-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++) {
        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:56:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   56 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:88:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:104:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  104 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

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