Submission #784089

#	Time	Username	Problem	Language	Result	Execution time	Memory
784089		rainboy	Lightning Rod (NOI18_lightningrod)	C11	66 / 100	2078 ms	226632 KiB

Main

#include <stdio.h>

#define N	10000000
#define INF	0x3f3f3f3f

unsigned int X = 12345;

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

int ll[N], rr[N];

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

		while (j < k) {
			int c = ll[ii[j]] != ll[i_] ? ll[ii[j]] - ll[i_] : rr[i_] - rr[ii[j]];

			if (c == 0)
				j++;
			else if (c < 0) {
				tmp = ii[i], ii[i] = ii[j], ii[j] = tmp;
				i++, j++;
			} else {
				k--;
				tmp = ii[j], ii[j] = ii[k], ii[k] = tmp;
		}
		}
		sort(ii, l, i);
		l = k;
	}
}

int main() {
	static int ii[N];
	int n, i, x, y, r, cnt;

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		scanf("%d%d", &x, &y);
		ll[i] = x - y, rr[i] = x + y;
	}
	for (i = 0; i < n; i++)
		ii[i] = i;
	sort(ii, 0, n);
	r = -INF, cnt = 0;
	for (i = 0; i < n; i++)
		if (r < rr[ii[i]])
			r = rr[ii[i]], cnt++;
	printf("%d\n", cnt);
	return 0;
}

Compilation message (stderr)

lightningrod.c: In function 'main':
lightningrod.c:40:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
lightningrod.c:42:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   42 |   scanf("%d%d", &x, &y);
      |   ^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 4
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 21 / 21
• Subtask 5: 26 / 26
• Subtask 6: 0 / 10
• Subtask 7: 0 / 20