UVa 10397 Connect the Campus

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最小生成树

Kruskal

#include<cmath>#include<iostream>#include<cstdio>#include<algorithm>using namespace std;struct A{    int x,y;    double z;}a[500010];int r[755];int find_(int x){    while(x!=r[x])        x=r[x];    return x;}int cmp(A a,A b){    return a.z<b.z;}int main(){    int n,m,i,j,k,c,b,x[755],y[755];    while(scanf("%d",&n)!=EOF)    {        for(i=1;i<=n;i++)            scanf("%d%d",&x[i],&y[i]);        for(i=1;i<=n;i++)            r[i]=i;        k=0;        for(i=1;i<=n;i++)            for(j=1;j<=n;j++){                if(i>j){                    double s=sqrt(  (x[i]-x[j])*(x[i]-x[j])+ (y[i]-y[j])*(y[i]-y[j]) );                    a[++k].x=i;                    a[k].y=j;                    a[k].z=s;                }            }        scanf("%d",&m);        while(m--){            scanf("%d%d",&c,&b);            int aa=find_(c);            int bb=find_(b);            if(aa!=bb){                r[aa]=bb;            }        }        sort(a+1,a+1+k,cmp);        double ans=0;        for(i=1;i<=k;i++)        {            int aa=find_(a[i].x);            int bb=find_(a[i].y);            if(aa!=bb){                r[aa]=bb;                ans=ans+a[i].z;            }        }        printf("%.2lf\n",ans);    }    return 0;}

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