HDOJ1007(二分法 TLE)

#include<iostream>  
#include<cstdio>  
#include<cmath>  
#include<algorithm>  


using namespace std;


#define N 100010
int n;


struct aa
{
double x, y;
}a[N],b[N];


bool cmp(aa a, aa b)
{
return a.y < b.y;
}




double caculate(aa a,aa b)
{
return sqrt(pow((a.x - b.x), 2) + pow((a.y - b.y), 2));
}


double minidis(int l, int r)
{
if (l+1==r) return caculate(a[l], a[r]);  //两个
if (l+2==r) return min(caculate(a[l], a[r]), min(minidis(l, l + 1), minidis(l + 1, r))); //三个
else
{
int m = (l + r) / 2;
int j1 = 0;
double mi = min(minidis(l, m), minidis(m + 1, r)); //只在左或右的情况
for(int i=l;i<=m;i++)
for (int j = m + 1; j <= r; j++)
{
if (fabs(a[i].y - a[j].y) >= mi) continue;
mi = min(mi, caculate(a[i], a[j]));
}
return mi;
}
}


int main()
{
while (cin >> n, n)
{
for (int i = 0; i < n; i++) cin >> a[i].x>>a[i].y;
sort(a, a + n, cmp);
double ans=minidis(0, n-1)/2;
printf("%.2lf\n", ans);
}
}