HDU 1875 畅通工程再续

传送门：http://acm.hdu.edu.cn/showproblem.php?pid=1875

简单的最小生成树

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;const int maxn=10000+5;
const double INF=1.0e20;struct Node{double x,y;
} isl[maxn];bool book[maxn];
double dis[maxn];double dist(double x1,double y1,double x2,double y2){return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}int main(){int T;scanf("%d",&T);while(T--){int n;scanf("%d",&n);for(int i=1;i<=n;i++){scanf("%lf%lf",&isl[i].x,&isl[i].y);}for(int i=1;i<=n;i++){dis[i]=INF;book[i]=false;}dis[1]=0;for(int k=1;k<=n;k++){int m=-1;double mx=INF;for(int i=1;i<=n;i++){if(!book[i]&&dis[i]<mx){m=i;mx=dis[i];}}if(m==-1)continue;book[m]=true;for(int i=1;i<=n;i++){if(!book[i]){double d=dist(isl[m].x,isl[m].y,isl[i].x,isl[i].y);if(d>=10.000000&&d<=1000.000001){if(d<dis[i]){dis[i]=d;}}}}}double ans=0;for(int i=1;i<=n;i++){ans+=dis[i];if(ans>=INF)break;}int flag=0;for(int i=1;i<=n;i++){if(book[i]==false){flag=1;break;}}if(ans>=INF||flag==1){printf("oh!\n");}else{printf("%.1lf\n",ans*100);}}return 0;
}