Submission #712337

#	Time	Username	Problem	Language	Result	Execution time	Memory
712337		rainboy	Remittance (JOI19_remittance)	C11	100 / 100	354 ms	28544 KiB

remittance

#include <stdio.h>

#define N	1000000
#define INF	0x3f3f3f3f3f3f3f3fLL

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

int solve(int *aa, int *bb, int n, long long k_) {
	int i;
	long long k, c;

	k = k_;
	for (i = n - 1; i > 0; i--) {
		if (aa[i] - k * 2 > bb[i])
			return -1;
		k = min(bb[i] - (aa[i] - k * 2), INF);
	}
	c = bb[0] - (aa[0] + k_ - k * 2);
	return c == 0 ? 0 : (c < 0 ? -1 : 1);
}

int main() {
	static int aa[N], bb[N];
	int n, i, same, zero;
	long long lower, upper;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		scanf("%d%d", &aa[i], &bb[i]);
	same = 1;
	for (i = 0; i < n; i++)
		if (aa[i] != bb[i]) {
			same = 0;
			break;
		}
	if (same) {
		printf("Yes\n");
		return 0;
	}
	zero = 1;
	for (i = 0; i < n; i++)
		if (bb[i] != 0) {
			zero = 0;
			break;
		}
	if (zero) {
		printf("No\n");
		return 0;
	}
	lower = 0, upper = INF;
	while (upper - lower > 1) {
		long long k = (lower + upper) / 2;

		if (solve(aa, bb, n, k) <= 0)
			lower = k;
		else
			upper = k;
	}
	printf(solve(aa, bb, n, lower) == 0 ? "Yes\n" : "No\n");
	return 0;
}

Compilation message (stderr)

remittance.c: In function 'main':
remittance.c:27:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
remittance.c:29:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |   scanf("%d%d", &aa[i], &bb[i]);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 15 / 15
• Subtask 2: 40 / 40
• Subtask 3: 45 / 45