这份代码在洛谷开O2能过

#include <iostream>
#include <algorithm>
#include <cmath>
#define x first
#define y second
using namespace std;
const int N = 1e5 + 10;
int x1,y1,x2,y2;
int n;
typedef pair<int,int> PII;
PII a[N];
PII dis1[N],dis2[N];
int b[N];
int f(int d){
	int l = 1,r = n;
	while(l < r){
		int mid = l + r + 1 >> 1;
		if(dis1[mid].x <= d) l = mid;
		else r = mid - 1;
	}
	return l;
}
int main(){
	scanf("%d %d %d %d",&x1,&y1,&x2,&y2);
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%d %d",&a[i].x,&a[i].y);
	for(int i=1;i<=n;i++){
		dis1[i].x = (x1 - a[i].x) * (x1 - a[i].x) + (y1 - a[i].y) * (y1 - a[i].y);
		dis1[i].y = i;
		dis2[i].x = (x2 - a[i].x) * (x2 - a[i].x) + (y2 - a[i].y) * (y2 - a[i].y);
		dis2[i].y = i;
	}
	sort(dis1 + 1,dis1 + n + 1);
	for(int i=1;i<=n;i++) b[dis1[i].y] = i;
	sort(dis2 + 1,dis2 + n + 1);
	int ans = 1e9;
	for(int i=1;i<=n;i++){
		int d = (x1 - a[i].x) * (x1 - a[i].x) + (y1 - a[i].y) * (y1 - a[i].y);
		int t = f(d);
		bool flag = false;
		for(int j=n;j>=1;j--){
			if(b[dis2[j].y] > t){
				ans = min(ans,d + dis2[j].x);
				flag = true;
				break;
			}
		}
		if(!flag) ans = min(ans,d);
	}
	printf("%d",ans);
	return 0;
}