图结构练习——最小生成树

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define MAXN 10000
#define inf 1<<28
int n, m;
int mapp[MAXN][MAXN];
int vis[MAXN], dis[MAXN];

void init()
{
    int i, j;
    for(i=1; i<=n; i++)
    {
        for(j=1; j<=n; j++)
        {
            mapp[i][j] = inf;
        }
        if(i==j)
            mapp[i][j] = 0;
    }
}
void prim()
{
    int i, j, pos, ans=0, min;
    for(i=2; i<=n; i++)
        dis[i] = mapp[1][i];
    vis[1] = 1;
    for(i=1; i<n; i++)
    {
        min = inf;
        for(j=2; j<=n; j++)
        {
            if(!vis[j] && dis[j]<min)
            {
                pos = j;
                min = dis[j];
            }
        }
        vis[pos] = 1;
        ans += min;

        for(j=2; j<=n; j++)
        {
             if(!vis[j] && mapp[pos][j]<dis[j])
                 dis[j] = mapp[pos][j];
        }
    }
    printf("%d\n", ans);
}

int main()
{
     int i, j;
     int u, v, c;
     while(~scanf("%d%d", &n, &m))
     {
         init();
         memset(vis, 0, sizeof(vis));
         memset(dis, 0, sizeof(dis));
         for(i=0; i<m; i++)
         {
             scanf("%d%d%d", &u, &v, &c);
             if(mapp[u][v]>c)//判重边
             {
                 mapp[u][v] = c;
                 mapp[v][u] = c;
             }
         }
         prim();
     }
}