POJ 1258 Agri-Net（最小生成树）

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
int n,coun;
struct road
{
    int f,t;
    int w;
};
road vil[10000+10];
int fa[10000+10];
int cmp(road a ,road b) {return a.w<b.w;}
int find(int x)
{
    return fa[x]==x?x:fa[x]=find(fa[x]);
}
int Kruskal()
{
    int ans=0;
    for(int i=0;i<coun;i++) fa[i]=i;
    sort(vil,vil+coun,cmp);
    for(int i=0;i<coun;i++)
    {
        int x=find(vil[i].f);
        int y=find(vil[i].t);
        if(x!=y)
        {
            fa[x]=y;
            ans+=vil[i].w;
        }
    }
    return ans;
}
int main()
{

    int i,j;
    while(scanf("%d",&n)!=EOF)
    {
        coun=0;
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=n;j++)
            {
                int waste;
                scanf("%d",&waste);
                if(i<j)
                {
                    vil[coun].f=i;
                    vil[coun].t=j;
                    vil[coun].w=waste;
                    coun++;
                }
            }
        }
        int ans=Kruskal();
        printf("%d\n",ans);
    }
    return  0;
}

#include<iostream>
using namespace std;

const int inf=100001;      //无限大

int n;   //农场数量
int dist[101][101];

int prim(void)
{
    int s=1;
    int m=1;
    bool u[101]={false};
    u[s]=true;

    int min_w;
    int prim_w=0;
    int point;
    int low_dis[101];

    /*Initial*/

    for(int i=1;i<=n;i++)
        low_dis[i]=inf;

    /*Prim Algorithm*/

    while(true)
    {
        if(m==n)
            break;
        min_w=inf;
        for(int i=2;i<=n;i++)
        {
            if(!u[i] && low_dis[i]>dist[s][i])
                low_dis[i] = dist[s][i];
            if(!u[i] && min_w>low_dis[i])
            {
                min_w = low_dis[i];
                point=i;
            }
        }
        s=point;
        u[s]=true;
        prim_w+=min_w;
        m++;
    }
    return prim_w;
}

int main(void)
{
    while(cin>>n)
    {
        /*Input*/

        for(int i=1;i<=n;i++)
            for(int j=1;j<=n;j++)
                cin>>dist[i][j];

        /*Prim Algorithm & Output*/

        cout<<prim()<<endl;
    }
    return 0;
}