제출 #1361872

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1361872		cavanar	COVID tests (CEOI24_covid)	C++20	13.93 / 100	788 ms	468 KiB

Main

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

/// 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::map<std::pair<int, int>, bool> asked;

bool ask(int l, int r) {
	std::pair<int, int> qr = std::make_pair(l, r);
	if (asked.count(qr)) {
		return asked[qr];
	}
	std::vector<bool> mask(N);
	for (; l <= r; l ++) {
		mask[l] = true;
	}
	return asked[qr] = test_students(mask);
}

std::vector<bool> find_positive() {
    std::vector<bool> answer(N);

	int window_size = std::min(100.0, 1.0 / P);

	for (int i = 0; i < N;) {
		int bs = -1;
		for (int l = i, r = std::min(N - 1, i + window_size); l <= r;) {
			int mi = (l + r) / 2;
			if (ask(l, mi)) {
				bs = mi, r = mi - 1;
			} else {
				l = mi + 1;
				r = std::min(N - 1, l + window_size);
			}
		}
		if (bs == -1) {
			i += window_size;
		} else {
			answer[bs] = true;
			i = bs + 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);

		asked.clear();
    }

    return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

Main.cpp: In function 'bool test_students(std::vector<bool>)':
Main.cpp:30:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     scanf(" %c", &answer);
      |     ~~~~~^~~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:84:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   84 |     scanf("%d %lf %d", &N, &P, &T);
      |     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:100:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |         scanf(" %c", &verdict);
      |         ~~~~~^~~~~~~~~~~~~~~~~

• 서브태스크 0: 0 / 0
• 서브태스크 1: 10 / 10
• 서브태스크 2: 3.93 / 90