Submission #537120

#	Time	Username	Problem	Language	Result	Execution time	Memory
537120		rainboy	별자리 2 (JOI14_constellation2)	C11	100 / 100	1758 ms	464 KiB

constellation2

#include <stdio.h>
#include <string.h>

#define N	3000

unsigned int X = 12345;

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

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

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]);
}

int o;

int compare(int i, int j) {
	int sgni = xx[i] < xx[o] || xx[i] == xx[o] && yy[i] < yy[o] ? -1 : 1;
	int sgnj = xx[j] < xx[o] || xx[j] == xx[o] && yy[j] < yy[o] ? -1 : 1;
	long long c;

	if (sgni != sgnj)
		return sgni - sgnj;
	c = cross(o, i, j);
	return c == 0 ? 0 : (c < 0 ? -1 : 1);
}

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 = compare(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 jj[N];
	static int kk[3], kk_[3];
	int n, m, i, j, j_, j1, j2, a, b;
	long long ans;

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		scanf("%d%d%d", &xx[i], &yy[i], &cc[i]);
		kk_[cc[i]]++;
	}
	ans = 0;
	for (i = 0; i < n; i++) {
		m = 0;
		for (j = 0; j < n; j++)
			if (j != i)
				jj[m++] = j;
		o = i, sort(jj, 0, m);
		memset(kk, 0, sizeof kk);
		for (j = 0, j_ = 0; j < m; j++) {
			j1 = jj[j];
			while (j_ < j + m && cross(o, j1, j2 = jj[j_ % m]) <= 0)
				kk[cc[j2]]++, j_++;
			a = cc[i], b = cc[j1];
			kk[b]--;
			if (i < j1) {
				kk_[a]--, kk_[b]--;
				ans += (long long) kk[(a + 1) % 3] * kk[(a + 2) % 3] * (kk_[(b + 1) % 3] - kk[(b + 1) % 3]) * (kk_[(b + 2) % 3] - kk[(b + 2) % 3]);
				kk_[a]++, kk_[b]++;
			}
		}
	}
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

constellation2.c: In function 'compare':
constellation2.c:21:45: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   21 |  int sgni = xx[i] < xx[o] || xx[i] == xx[o] && yy[i] < yy[o] ? -1 : 1;
      |                              ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
constellation2.c:22:45: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   22 |  int sgnj = xx[j] < xx[o] || xx[j] == xx[o] && yy[j] < yy[o] ? -1 : 1;
      |                              ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
constellation2.c: In function 'main':
constellation2.c:59:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   59 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
constellation2.c:61:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 |   scanf("%d%d%d", &xx[i], &yy[i], &cc[i]);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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