답안 #5165

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
5165	2014-02-13T19:56:49 Z	cki86201	초록색 삼각형 (YDX13_green)	C++	0 / 1	1224 ms	1352 KB

C

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

typedef long long ll;

const double PI = 3.14159265358979;

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);
	int i, j;
	for(i=1;i<=n;i++)scanf("%d%d",x+i,y+i);
	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[ord[j]] - 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]/n/(n-1)/(n-2)) * (x[nj] - x[i]) - ((double)now[0]/n/(n-1)/(n-2)) * (y[nj] - y[i]);
		}
	}
	printf("%.12f",ans);
	return 0;
}

Subtask #1

0.0 / 1.0

#	결과	실행 시간	메모리	Grader output
1	Correct	0 ms	1352 KB	Output is correct
2	Correct	0 ms	1352 KB	Output is correct
3	Correct	0 ms	1352 KB	Output is correct
4	Correct	0 ms	1352 KB	Output is correct
5	Correct	0 ms	1352 KB	Output is correct
6	Correct	0 ms	1352 KB	Output is correct
7	Correct	0 ms	1352 KB	Output is correct
8	Correct	0 ms	1352 KB	Output is correct
9	Correct	0 ms	1352 KB	Output is correct
10	Correct	0 ms	1352 KB	Output is correct
11	Correct	220 ms	1352 KB	Output is correct
12	Correct	424 ms	1352 KB	Output is correct
13	Correct	268 ms	1352 KB	Output is correct
14	Correct	1100 ms	1352 KB	Output is correct
15	Correct	108 ms	1352 KB	Output is correct
16	Correct	1056 ms	1352 KB	Output is correct
17	Correct	64 ms	1352 KB	Output is correct
18	Correct	168 ms	1352 KB	Output is correct
19	Correct	280 ms	1352 KB	Output is correct
20	Correct	0 ms	1352 KB	Output is correct
21	Correct	1204 ms	1352 KB	Output is correct
22	Correct	1212 ms	1352 KB	Output is correct
23	Correct	1208 ms	1352 KB	Output is correct
24	Correct	1216 ms	1352 KB	Output is correct
25	Correct	1224 ms	1352 KB	Output is correct
26	Correct	1212 ms	1352 KB	Output is correct
27	Correct	1212 ms	1352 KB	Output is correct
28	Correct	1212 ms	1352 KB	Output is correct
29	Correct	1212 ms	1352 KB	Output is correct
30	Correct	1212 ms	1352 KB	Output is correct
31	Incorrect	0 ms	1352 KB	Output isn't correct