제출 #1194334

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1194334		franuch	COVID tests (CEOI24_covid)	C++20	73.43 / 100	825 ms	408 KiB

Main

#include <cassert>
#include <cstdio>
#include <string>
#include <vector>
#include <bits/stdc++.h>
typedef int ll;
using namespace std;
typedef pair<ll, ll> pll;
#define vc 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> find_positive() {
	ll d = max(1, ll(1.0 / P));
	vc<bool> res(N, false);
	for (ll l = 0; l < N; ) {
		ll r = min(l + d - 1, N - 1);
		vc<bool> mask(N);
		for (ll i = l; i <= r; i++)
			mask[i] = true;
		bool x = test_students(mask);
		if (not x) {
			l = r + 1;
			continue;
		}
		while (l < r) {
			ll s = (l + r) / 2;
			mask.assign(N, 0);
			for (ll i = l; i <= s; i++)
				mask[i] = true;
			x = test_students(mask);
			if (x)
				r = s;
			else
				l = s + 1;
		}
		res[l] = true;
		l++;
	}
	return res;
}

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;
}

컴파일 시 표준 에러 (stderr) 메시지

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:34:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:76:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:92:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   92 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 0: 0 / 0
• Subtask 1: 10 / 10
• Subtask 2: 63.43 / 90