Codeforces Round #352 (Div. 2) C. Recycling Bottles

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#define maxn 100005
#define INF 1e18
using namespace std;

double x[maxn], y[maxn];
double a1, a2, b1, b2, t1, t2, sum;
int n;
void solve(double c1, double c2, double &s, int &p){

s = INF;
for(int i = 1; i <= n; i++){
if(x[i] >= 0){
double dd = sqrt((x[i]-c1)*(x[i]-c1) + (y[i]-c2) * (y[i] - c2));
double d = sqrt((x[i]-t1) * (x[i]-t1) + (y[i]-t2) * (y[i]-t2));
if(s > dd - d){
s = dd - d;
p = i;
}
}
}
}
int main(){

//freopen("in.txt", "r", stdin);

scanf("%lf%lf%lf%lf%lf%lf", &a1, &a2, &b1, &b2, &t1, &t2);
scanf("%d", &n);
for(int i = 1; i <= n; i++){
scanf("%lf%lf", x+i, y+i);
sum += 2 * sqrt((x[i]-t1) * (x[i]-t1) + (y[i]-t2) * (y[i]-t2));
}
double s1, s2;
int p1, p2;
solve(a1, a2, s1, p1);
solve(b1, b2, s2, p2);
if((s1 >= 0 && s2 >= 0) || s1 * s2 <= 0)
sum += min(s1, s2);
else{
if(p1 != p2)
sum += s1 + s2;
else{
double c1, c2;
x[p1] = -1;
solve(a1, a2, c1, p1);
solve(b1, b2, c2, p2);
if(c1 >= 0)
c1 = 0;
if(c2 >= 0)
c2 = 0;
sum += min(s1 + c2, s2 + c1);
}
}
printf("%.12lf\n", sum);

return 0;
}