Submission #508771

#	Time	Username	Problem	Language	Result	Execution time	Memory
508771		rainboy	별자리 (JOI12_constellation)	C11	10 / 100	1 ms	332 KiB

constellation

/* https://ioi.te.lv/locations/ioi06/contest/day2/points/points_sol.pdf */
#include <stdio.h>

#define N	10

unsigned int X;

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

int xx[N], yy[N], cc[N], o;

long long cross(int i, int j, int k) {
	return (long long) (xx[j] - xx[i]) * (yy[k] - yy[i]) - (long long) (xx[k] - xx[i]) * (yy[j] - yy[i]);
}

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) {
			long long c = cross(o, ii[j], i_);

			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, cnt, h, i, b, ans, comp;

	scanf("%d", &n);
	o = -1;
	for (i = 0; i < n; i++) {
		scanf("%d%d%d", &xx[i], &yy[i], &cc[i]), cc[i]--;
		if (o == -1 || xx[o] > xx[i] || xx[o] == xx[i] && yy[o] > yy[i])
			o = i;
		ii[i] = i;
	}
	ii[0] = o, ii[o] = 0;
	sort(ii, 1, n);
	cnt = 0;
	for (i = 0; i < n; i++) {
		while (cnt >= 2 && cross(ii[cnt - 2], ii[cnt - 1], ii[i]) >= 0)
			cnt--;
		ii[cnt++] = ii[i];
	}
	ans = 0;
	for (b = 1; b < (1 << n) - 1; b++) {
		int k;

		comp = 1;
		for (i = 0; i < n; i++)
			if (cc[i] != -1 && cc[i] != (b >> i & 1)) {
				comp = 0;
				break;
			}
		if (!comp)
			continue;
		k = 0;
		for (h = 0; h < cnt; h++)
			if ((b >> ii[h] & 1) != (b >> ii[(h + 1) % cnt] & 1))
				k++;
		if (k <= 2)
			ans++;
	}
	printf("%d\n", ans);
	return 0;
}

Compilation message (stderr)

constellation.c: In function 'main':
constellation.c:48:50: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   48 |   if (o == -1 || xx[o] > xx[i] || xx[o] == xx[i] && yy[o] > yy[i])
      |                                   ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
constellation.c:44:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   44 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
constellation.c:47:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   47 |   scanf("%d%d%d", &xx[i], &yy[i], &cc[i]), cc[i]--;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10