Kruskal最小生成树

并查集+kruskal==>MST

效率很低

#include <iostream>

using namespace std;



#define MAX 105   //自己设置最大值



// father[x]表示x的父节点

int father[MAX];

// rank[x]表示x的秩

int rank[MAX];



typedef struct

{

    int i,j;

    int distance;

} E;



E edges[MAX*MAX];



// 初始化

void Make_Set(int n)

{

    for(int i=1; i<=n; ++i)

    {

        father[i] = i;

        rank[i] = 0;

    }

}



// 查找

int Find_Set(int x)

{

    if(x != father[x])

        return Find_Set(father[x]);

    return x;

}



// 合并

void Union(int x, int y)

{

    x = Find_Set(x);

    y = Find_Set(y);

    if(x == y)  // x,y在同一个集合

        return;

    if(rank[x] > rank[y])

        father[y] = x;

    else if(rank[x] < rank[y])

        father[x] = y;

    else

    {

        rank[y]++;

        father[x] = y;

    }

}



bool myfunction ( const E a , const E b )

{

    return (a.distance<b.distance);

}



int main()

{

    freopen("input.txt","r",stdin);

    int i,j,n,m,u,v;

    int count,Sum;

    while(cin>>n&&n!=0)

    {

        count=Sum=0;

        for(i=0; i<n; i++)

            for(j=0; j<n; j++)

            {

                edges[i*n+j].i=i;

                edges[i*n+j].j=j;

                cin>>edges[i*n+j].distance;

            }

        sort(edges,edges+(n*n),myfunction);

        Make_Set(n);

        for(i=0; i<n*n; i++)

        {

            if(count==n-1) break;

            if(edges[i].i!=edges[i].j&&(Find_Set(edges[i].i)!=Find_Set(edges[i].j)))

               {

                   Union(edges[i].i,edges[i].j);

                   Sum+=edges[i].distance;

               }

        }

        cout<<Sum<<endl;

    }

    return 0;

}