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
#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;
}
# 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