poj 1258 prim最小生成树

#include <iostream>using namespace std;int a[105][105],b[105],n;int prim(int ii){   int i,j,k,min,ans=0,t;    for(i=0;i<n;i++)      b[i]=a[ii][i];    b[ii]=-1;    for(i=1;i<n;i++)    {        for(min=2<<20,j=0;j<n;j++)            if(min>b[j]&&b[j]!=-1) min=b[j],t=j;        ans+=min; b[t]=-1;        for(j=0;j<n;j++)        if(a[t][j]<b[j]) b[j]=a[t][j];    }    return ans;}int main(){   int i,j;    while(cin>>n)    {    for(i=0;i<n;i++)    for(j=0;j<n;j++)      cin>>a[i][j];    cout<<prim(0)<<endl;	    }    return 0;}