답안 #5221

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
5221	2014-02-18T05:27:37 Z	kriii	초록색 삼각형 (YDX13_green)	C++	0 / 1	216 ms	1148 KB

C

#include <stdio.h>
#include <algorithm>
using namespace std;

struct point{long long x,y;} P[2020],Q[2020];
bool cmp1(const point& a, const point& b){return a.y == b.x ? a.x < b.x : a.y < b.y;}
bool cmp2(const point& a, const point& b){return a.x * b.y - a.y * b.x < 0;}

int main()
{
	int N;
	scanf ("%d",&N);
	for (int i=0;i<N;i++){
		scanf ("%lld %lld",&P[i].x,&P[i].y);
	}
	sort(P,P+N,cmp1);

	double ans = 0;
	for (int i=0;i<N;i++){
		int c = 0;
		for (int j=i+1;j<N;j++){
			Q[c].x = P[j].x - P[i].x;
			Q[c].y = P[j].y - P[i].y;
			c++;
		}
		sort(Q,Q+c,cmp2);
		
		double sx = 0, sy = 0;
		for (int j=0;j<c;j++){
			ans += Q[j].x * sy - Q[j].y * sx;
			sx += Q[j].x;
			sy += Q[j].y;
		}
	}

	if (N >= 3){
		ans /= N;
		ans /= N-1;
		ans /= N-2;
		ans *= 3;
	}

	printf ("%.12lf\n",ans);

	return 0;
}

Subtask #1

0.0 / 1.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	1148 KB	Output is correct
2	Correct	0 ms	1148 KB	Output is correct
3	Correct	0 ms	1148 KB	Output is correct
4	Correct	0 ms	1148 KB	Output is correct
5	Correct	0 ms	1148 KB	Output is correct
6	Correct	0 ms	1148 KB	Output is correct
7	Correct	0 ms	1148 KB	Output is correct
8	Correct	0 ms	1148 KB	Output is correct
9	Correct	0 ms	1148 KB	Output is correct
10	Correct	0 ms	1148 KB	Output is correct
11	Correct	36 ms	1148 KB	Output is correct
12	Correct	68 ms	1148 KB	Output is correct
13	Correct	44 ms	1148 KB	Output is correct
14	Correct	192 ms	1148 KB	Output is correct
15	Correct	16 ms	1148 KB	Output is correct
16	Correct	184 ms	1148 KB	Output is correct
17	Correct	8 ms	1148 KB	Output is correct
18	Correct	28 ms	1148 KB	Output is correct
19	Correct	44 ms	1148 KB	Output is correct
20	Correct	0 ms	1148 KB	Output is correct
21	Correct	212 ms	1148 KB	Output is correct
22	Correct	212 ms	1148 KB	Output is correct
23	Correct	212 ms	1148 KB	Output is correct
24	Correct	212 ms	1148 KB	Output is correct
25	Correct	208 ms	1148 KB	Output is correct
26	Correct	212 ms	1148 KB	Output is correct
27	Correct	212 ms	1148 KB	Output is correct
28	Correct	212 ms	1148 KB	Output is correct
29	Correct	216 ms	1148 KB	Output is correct
30	Correct	212 ms	1148 KB	Output is correct
31	Incorrect	0 ms	1148 KB	Output isn't correct