Agri-Net

poj1258:http://poj.org/problem?id=1258

题意：生成树的模板题。简单题。

#include<iostream>
#include<cstring>
#include<cstdio>
#include<algorithm>
#define INF 100000000
#define MAXN 103
using namespace std;
int n,m;
int Edge[MAXN][MAXN];
int lowcost[MAXN];
int nearvex[MAXN];
void prim(int u0){
    int i,j;
    int sumweight=0;
    for( i=1;i<=n;i++){
        lowcost[i]=Edge[u0][i];
        nearvex[i]=u0;
    }
    nearvex[u0]=-1;
    for( i=1;i<n;i++){
        int min=INF;
        int v=-1;
        for(j=1;j<=n;j++){
            if(nearvex[j]!=-1&&lowcost[j]<min){
                v=j;min=lowcost[j];
            }
        }
        if(v!=-1){
            nearvex[v]=-1;
            sumweight+=lowcost[v];
            for(j=1;j<=n;j++){
                if(nearvex[j]!=-1&&Edge[v][j]<lowcost[j]){
                    lowcost[j]=Edge[v][j];
                    nearvex[j]=v;
                    
                }
            }
        }
    }
    printf("%d
",sumweight);
}
int main(){
    int i,j;
    int u,v,w;
    while(~scanf("%d",&n)){
    memset(Edge,0,sizeof(Edge));
    for(i=1;i<=n;i++){
        for(j=1;j<=n;j++){
          scanf("%d",&w);    
          Edge[i][j]=Edge[j][i]=w;
        }
    }
    for( i=1;i<=n;i++)
      for( j=1;j<=n;j++){
          if(i==j)Edge[i][j]=0;
          else if(Edge[i][j]==0)Edge[i][j]=INF;
      }
      prim(1);
}
}