답안 #5168

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
5168	2014-02-13T20:52:20 Z	cki86201	초록색 삼각형 (YDX13_green)	C++	0 / 1	1028 ms	79628 KB

C

#include<stdio.h>
#include<algorithm>
#include<math.h>
#include<vector>

typedef long long ll;

const double PI = 3.141592653589793238;

int x[2020], y[2020], ord[2020];
double an[2020];
int n;

bool comp(const int &a,const int &b){return an[a] < an[b];}

int main()
{
	scanf("%d",&n);
	std::vector <int> v(n*10000);
	int i, j;
	for(i=1;i<=n;i++)scanf("%d%d",x+i,y+i);
	if(n<=2){printf("0");return 0;}
	for(i=1;i<=n;i++)ord[i] = i;
	double ans = 0;
	for(i=1;i<=n;i++){
		for(j=1;j<=n;j++)an[j] = atan2(y[j] - y[i], x[j] - x[i]);
		std::sort(ord+1,ord+1+n,comp);
		ll now[2] = {0,0};
		int t = 1;
		double na = 0;
		for(j=1;j<=n;j++){
			int nj = ord[j];
			if(j>1)na -= fmod(an[nj] - an[ord[j-1]] + 2*PI, 2*PI);
			while(na < PI){
				now[0] += x[ord[t]] - x[i];
				now[1] += y[ord[t]] - y[i];
				na += fmod(an[ord[t%n+1]] - an[ord[t]] + 2*PI, 2*PI);
				t = t%n + 1;
			}
			now[0] -= x[nj] - x[i], now[1] -= y[nj] - y[i];
			ans += (double)now[1] * (x[nj] - x[i]) - (double)now[0] * (y[nj] - y[i]);
		}
	}
	printf("%.12f",ans/n/(n-1)/(n-2));
	return 0;
}

Subtask #1

0.0 / 1.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	1660 KB	Output is correct
2	Correct	0 ms	1892 KB	Output is correct
3	Correct	0 ms	1500 KB	Output is correct
4	Correct	0 ms	1660 KB	Output is correct
5	Correct	0 ms	1696 KB	Output is correct
6	Correct	0 ms	1736 KB	Output is correct
7	Correct	0 ms	1776 KB	Output is correct
8	Correct	0 ms	1816 KB	Output is correct
9	Correct	0 ms	1852 KB	Output is correct
10	Correct	0 ms	1892 KB	Output is correct
11	Correct	184 ms	35680 KB	Output is correct
12	Correct	360 ms	48416 KB	Output is correct
13	Correct	220 ms	39040 KB	Output is correct
14	Correct	928 ms	75956 KB	Output is correct
15	Correct	92 ms	25800 KB	Output is correct
16	Correct	892 ms	74668 KB	Output is correct
17	Correct	60 ms	20252 KB	Output is correct
18	Correct	152 ms	31620 KB	Output is correct
19	Correct	236 ms	39744 KB	Output is correct
20	Correct	0 ms	2244 KB	Output is correct
21	Correct	1016 ms	79628 KB	Output is correct
22	Correct	1004 ms	79628 KB	Output is correct
23	Correct	1020 ms	79628 KB	Output is correct
24	Correct	1024 ms	79628 KB	Output is correct
25	Correct	1024 ms	79628 KB	Output is correct
26	Correct	1020 ms	79628 KB	Output is correct
27	Correct	1020 ms	79628 KB	Output is correct
28	Correct	1008 ms	79628 KB	Output is correct
29	Correct	1024 ms	79628 KB	Output is correct
30	Correct	1028 ms	79628 KB	Output is correct
31	Incorrect	0 ms	1500 KB	Output isn't correct