Submission #5220

#	Submission time	Handle	Problem	Language	Result	Execution time	Memory
5220	2014-02-18T05:26:46 Z	kriii	초록색 삼각형 (YDX13_green)	C++	0 / 1	36 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);
		
		long long 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

#	Verdict	Execution time	Memory	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	Incorrect	36 ms	1148 KB	Output isn't correct
12	Halted	0 ms	0 KB	-