平面上给定n条线段，找出一个点，使这个点到这n条线段的距离和最小。

题目：平面上给定n条线段，找出一个点，使这个点到这n条线段的距离和最小。

源码如下：

#include <iostream>  
#include <string.h>  
#include <stdlib.h>  
#include <stdio.h>  
#include <time.h>  
#include <math.h>  
  
#define N 1005  
#define eps 1e-8     //搜索停止条件阀值  
#define INF 1e99       
#define delta 0.98   //温度下降速度  
#define T 100        //初始温度  
  
using namespace std;  
  
int dx[4] = {0, 0, -1, 1};  
int dy[4] = {-1, 1, 0, 0};  //上下左右四个方向  
  
struct Point  
{  
    double x, y;  
};  
  
Point s[N], t[N];  
  
double cross(Point A, Point B, Point C)    
{    
    return (B.x - A.x) * (C.y - A.y) - (B.y - A.y) * (C.x - A.x);    
}    
  
double multi(Point A, Point B, Point C)    
{    
    return (B.x - A.x) * (C.x - A.x) + (B.y - A.y) * (C.y - A.y);    
}    
  
double dist(Point A, Point B)  
{  
    return sqrt((A.x - B.x) * (A.x - B.x) + (A.y - B.y) * (A.y - B.y));  
}  
  
double GetDist(Point A, Point B, Point C)    
{    
    if(dist(A, B) < eps) return dist(B, C);    
    if(multi(A, B, C) < -eps) return dist(A, C);    
    if(multi(B, A, C) < -eps) return dist(B, C);    
    return fabs(cross(A, B, C) / dist(A, B));    
}    
  
double GetSum(Point s[], Point t[], int n, Point o)  
{  
    double ans = 0;  
    while(n--)  
        ans += GetDist(s[n], t[n], o);  
    return ans;  
}  
  
double Search(Point s[], Point t[], int n, Point &o)  
{  
    o = s[0];      
    double tem = T;        
    double ans = INF;  
    while(tem > eps)  
    {  
        bool flag = 1;  
        while(flag)  
        {  
            flag = 0;  
            for(int i = 0; i < 4; i++)    //上下左右四个方向  
            {  
                Point z;  
                z.x = o.x + dx[i] * tem;  
                z.y = o.y + dy[i] * tem;  
                double tp = GetSum(s, t, n, z);  
                if(ans > tp)  
                {  
                    ans = tp;  
                    o = z;  
                    flag = 1;  
                }  
            }  
        }  
        tem *= delta;  
    }  
    return ans;  
}  
  
int main()  
{  
    int n;  
    while(scanf("%d", &n) != EOF)  
    {  
        for(int i = 0; i < n; i++)  
            scanf("%lf %lf %lf %lf", &s[i].x, &s[i].y, &t[i].x, &t[i].y);  
        Point o;  
        double ans = Search(s, t, n, o);  
        printf("%.1lf %.1lf %.1lf
", o.x, o.y, ans);    
    }  
    return 0;  
}