제출 #531877

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
531877		rainboy	구경하기 (JOI13_watching)	C11	100 / 100	264 ms	15956 KiB

watching

#include <stdio.h>

#define N	2000

int min(int a, int b) { return a < b ? a : b; }

unsigned int X = 12345;

int rand_() {
	return (X *= 3) >> 1;
}

void sort(int *aa, int l, int r) {
	while (l < r) {
		int i = l, j = l, k = r, a = aa[l + rand_() % (r - l)], tmp;

		while (j < k)
			if (aa[j] == a)
				j++;
			else if (aa[j] < a) {
				tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = aa[j], aa[j] = aa[k], aa[k] = tmp;
			}
		sort(aa, l, i);
		l = k;
	}
}

int main() {
	static int xx[N], dp[N + 1][N + 1];
	int n, k_, l_, i, j1, j2, k, lower, upper;

	scanf("%d%d%d", &n, &k_, &l_), k_ = min(k_, n), l_ = min(l_, n);
	for (i = 0; i < n; i++)
		scanf("%d", &xx[i]);
	sort(xx, 0, n);
	lower = 0, upper = 0x3f3f3f3f;
	while (upper - lower > 1) {
		int w = (lower + upper) / 2, ok;

		for (i = 0; i <= n; i++)
			for (k = 0; k <= k_; k++)
				dp[i][k] = l_ + 1;
		dp[0][0] = 0;
		for (i = 0, j1 = 0, j2 = 0; i <= n; i++) {
			while (j1 < n && xx[j1] - xx[i] < w)
				j1++;
			while (j2 < n && xx[j2] - xx[i] < w * 2)
				j2++;
			for (k = 0; k <= k_; k++) {
				if (k < k_)
					dp[j1][k + 1] = min(dp[j1][k + 1], dp[i][k]);
				if (dp[i][k] < l_)
					dp[j2][k] = min(dp[j2][k], dp[i][k] + 1);
			}
		}
		ok = 0;
		for (k = 0; k <= k_; k++)
			if (dp[n][k] <= l_) {
				ok = 1;
				break;
			}
		if (ok)
			upper = w;
		else
			lower = w;
	}
	printf("%d\n", upper);
	return 0;
}

컴파일 시 표준 에러 (stderr) 메시지

watching.c: In function 'main':
watching.c:36:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   36 |  scanf("%d%d%d", &n, &k_, &l_), k_ = min(k_, n), l_ = min(l_, n);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
watching.c:38:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   38 |   scanf("%d", &xx[i]);
      |   ^~~~~~~~~~~~~~~~~~~

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50