prim求MST

PRIM==>>MST模板

#include <iostream>



using namespace std;

#define typec int

#define V 3

const typec inf=0x3f3f3f3f;

int vis[V];

typec lowc[V];

/*==================================================*\

 | Prim求MST

 | INIT: cost[][]耗费矩阵(inf为无穷大);

 | CALL: prim(cost, n); 返回-1代表原图不连通;

\*==================================================*/

typec prim(typec cost[][V],int n)

{

    int i,j,p;

    typec minc,res=0;

    memset(vis,0,sizeof(vis));

    vis[0]=1;

    for(i=1; i<n; i++) lowc[i]=cost[0][i];

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

    {

        minc=inf;

        p=-1;

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

        {

            if(0==vis[j]&&minc>lowc[j])

            {

                minc=lowc[j];

                p=j;

            }

        }

        if(inf==minc) return -1;

        res+=minc;

        vis[p]=1;

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

            if(0==vis[j]&&lowc[j]>cost[p][j])lowc[j]=cost[p][j];

    }

    return res;

}





int main()

{

    int cost[3][3]= {0,990,692,990,0,179,692,179,0};

    cout << prim(cost,3) << endl;

    return 0;

}