poj 1751 Highways MST

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水到家的一道题，居然WA了3次……没注意到距离是double……没有输出的话要输出一行空行

/*author:jxylang:C/C++university:China,Xidian University**If you need to reprint,please indicate the source***/#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <cmath>#define INF 1E9using namespace std;double d[751];double dis[751][751];bool vis[751];int near[751];struct node{    int x,y;};node org[751];int n;int prim(){    double Min,ans=0;    int K=n,i,t,now=0;    while(K--)    {        Min=INF;        for(i=0;i<n;i++)            if(!vis[i]&&d[i]<Min)                Min=d[i],now=i;        vis[now]=1;        if(now)        {            ans+=Min;            if(Min)printf("%d %d\n",now+1,near[now]+1);        }        for(i=0;i<n;i++)        {            if(vis[i]||d[i]<=dis[now][i])continue;            d[i]=dis[now][i];near[i]=now;        }    }    return ans;}int main(){    int i,j,m,a,b,T=0;    while(~scanf("%d",&n))    {        memset(vis,0,sizeof(vis));        memset(d,127,sizeof(d));        for(i=0;i<n;i++)          scanf("%d%d",&org[i].x,&org[i].y);        for(i=0;i<n;i++)         for(j=0;j<=i;j++)             dis[j][i]=dis[i][j]=sqrt((org[i].x-org[j].x)*(org[i].x-org[j].x)+(org[i].y-org[j].y)*(org[i].y-org[j].y));        scanf("%d",&m);        for(i=0;i<m;i++)        {            scanf("%d%d",&a,&b);            dis[a-1][b-1]=dis[b-1][a-1]=0;        }        if(!prim())puts("");    }}