Submission #703029

#	Time	Username	Problem	Language	Result	Execution time	Memory
703029		rainboy	Star triangles (IZhO11_triangle)	C11	100 / 100	143 ms	12580 KiB

triangle

#include <stdio.h>

#define N	300000

unsigned int X = 12345;

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

int *zz;

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)
			if (zz[ii[j]] == zz[i_])
				j++;
			else if (zz[ii[j]] < zz[i_]) {
				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 xx[N], yy[N], ii[N], kkx[N], kky[N];
	int n, h, i, j, x, y;
	long long ans;

	scanf("%d", &n);
	for (i = 0; i < n; i++)
		scanf("%d%d", &xx[i], &yy[i]);
	for (i = 0; i < n; i++)
		ii[i] = i;
	zz = xx, sort(ii, 0, n);
	for (i = 0; i < n; i = j) {
		x = xx[ii[i]], j = i + 1;
		while (j < n && xx[ii[j]] == x)
			j++;
		for (h = i; h < j; h++)
			kkx[ii[h]] = j - i;
	}
	zz = yy, sort(ii, 0, n);
	for (i = 0; i < n; i = j) {
		y = yy[ii[i]], j = i + 1;
		while (j < n && yy[ii[j]] == y)
			j++;
		for (h = i; h < j; h++)
			kky[ii[h]] = j - i;
	}
	ans = 0;
	for (i = 0; i < n; i++)
		ans += (long long) (kkx[i] - 1) * (kky[i] - 1);
	printf("%lld\n", ans);
	return 0;
}

Compilation message (stderr)

triangle.c: In function 'main':
triangle.c:37:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   37 |  scanf("%d", &n);
      |  ^~~~~~~~~~~~~~~
triangle.c:39:3: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |   scanf("%d%d", &xx[i], &yy[i]);
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 100 / 100