ZOJ 1914 Arctic Network 最小生成树

最小生成树，已经开通s条。用并查集实现

#include<iostream>#include<cstdio>#include<string.h>#include<algorithm>#include<cmath>using namespace std;#define inf 0x3f3f3f3fconst int N=502;int father[N],x[N],y[N],cnt;struct node{int x,y;double d;}e[N*N];int find(int v){if(father[v]!=v)father[v]=find(father[v]);return father[v];}double calc(int i,int j){double rst=(x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]);return sqrt(rst);}int cmp(node a,node b){return a.d<b.d;}int main(){int tt,s,p;for(cin>>tt;tt>0;tt--){//s个点有cin>>s>>p;for(int i=0;i<=p;i++)father[i]=i;int u,v;for(int i=1;i<=p;i++)scanf("%d %d",&x[i],&y[i]);cnt=0;for(int i=1;i<=p;i++)for(int j=i+1;j<=p;j++)e[cnt].x=i,e[cnt].y=j,e[cnt++].d=calc(i,j);sort(e,e+cnt,cmp);int tot=p-1-s;double ans=0;for(int i=0;i<cnt;i++){u=find(e[i].x),v=find(e[i].y);//printf("%.2lf--%d %d\n",e[i].d,u,v);if(u!=v){father[u]=v;ans=max(ans,e[i].d);if(tot--==0)break;}}printf("%.2lf\n",ans);}return 0;}