CodeForces 617C Watering Flowers

#include<cstdio>
#include<cstring>
#include<vector>
#include<cmath>
#include<queue>
#include<list>
#include<algorithm>
using namespace std;

const int maxn=2000+10;
struct point
{
    long long x,y;
    long long len2;//与圆心p1的距离的平方
}p[maxn],p1,p2;
int n;

long long Len2(point a,point b)
{
    return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y);
}

bool cmp(const point&a,const point&b)
{
    return a.len2<b.len2;
}

int main()
{
    scanf("%d",&n);
    scanf("%lld%lld",&p1.x,&p1.y);
    scanf("%lld%lld",&p2.x,&p2.y);

    for(int i=0;i<n;i++) scanf("%lld%lld",&p[i].x,&p[i].y);
    for(int i=0;i<n;i++) p[i].len2=Len2(p1,p[i]);

    long long ans=-1;
    sort(p,p+n,cmp);

    for(int i=0;i<n;i++)
    {
        long long Max=0;
        for(int j=i+1;j<n;j++)
            Max=max(Max,Len2(p2,p[j]));
        if(ans==-1) ans=Max+p[i].len2;
        else ans=min(ans,Max+p[i].len2);
    }
    long long Max=0;
    for(int i=0;i<n;i++)
        Max=max(Max,Len2(p2,p[i]));
    ans=min(ans,Max);
    printf("%lld\n",ans);
    return 0;
}