60分wa求救

#include<bits/stdc++.h>
using namespace std;
int n;
int abs(int a){return a<0?-a:a;}
struct str{
	int x,y,sum;
}f[200039];
int _x,_y;
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%d%d",&f[i].x,&f[i].y);
	}
	double k=100000;
	for(int i=1;i<=n;i++){
		for(int j=i+1;j<=n;j++){
			_x=abs(f[j].x-f[i].x);
			_y=abs(f[j].y-f[i].y);
			if(k>((double)_x*_x+_y*_y))
			k=((double)_x*_x+_y*_y);
		}
	}
	printf("%.4lf\n",sqrt(k));
}