poj 2420

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cmath>
 4 #include <stdlib.h>
 5 #define pii pair<int,int>
 6 using namespace std;
 7 typedef double db;
 8 const db INF = 1e100;
 9 const db delta = 0.98;
10 const db eps = 1e-8;
11 int sign(db k){
12     if (k>eps) return 1; else if (k<-eps) return -1; return 0;
13 }
14 int cmp(db k1,db k2){return sign(k1-k2);}
15 struct point {
16     db x,y;
17     point operator - (const point &k1)const { return point{x-k1.x,y-k1.y};};
18     db abs(){ return sqrt(x*x+y*y);}
19     db dis(point k1){ return ((*this)-k1).abs();}
20 };
21 db random(){
22     return (rand()&1?1:-1)*rand()*1.0/32767;
23 }
24 int n;point p[105];
25 point ans[10];
26 db F(point x){
27     db res = 0;
28     for(int i=0;i<n;i++){
29         res+=x.dis(p[i]);
30     }
31     return res;
32 }
33 void SA(){
34     db t = 100;
35     while (t>eps){
36         for(int i=0;i<10;i++){
37             db tmp = F(ans[i]);
38             for(int j=0;j<10;j++){
39                 point _x=point{ans[i].x+random()*t,ans[i].y+random()*t};
40                 db f = F(_x);
41                 if(tmp>f) {
42                     tmp = f;
43                     ans[i]=_x;
44                 }
45             }
46         }
47         t*=delta;
48     }
49     db ed = INF;
50     for(int i=0;i<10;i++)
51         ed=min(ed,F(ans[i]));
52     printf("%.0f",ed);
53 }
54 int main(){
55     ios::sync_with_stdio(false);
56     scanf("%d",&n);
57     for(int i=0;i<n;i++){
58         scanf("%lf%lf",&p[i].x,&p[i].y);
59     }
60     SA();
61 }