Kruscal示例程序

其中n和m分别表示图的顶点数和边数。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<string>
#include<cmath>
#include<map>
#include<algorithm>
using namespace std;

const int maxn=11;
const int maxm=20;
int n,m;

struct Edge
{
    int u,v,w;
} edges[maxm];

class set
{
public:
    void makeset(int n)
    {
        for(int i=0; i<n; i++)
        {
            father[i]=i;
            rank[i]=1;
        }
    }
    int findset(int x)
    {
        if(x!=father[x])
            father[x]=findset(father[x]);
        return father[x];
    }
    void unionset(int x,int y)
    {
        x=findset(x);
        y=findset(y);
        if(x==y)  return;
        if(rank[x]>rank[y])
        {
            father[y]=x;
            rank[x]+=rank[y];
        }
        else
        {
            father[x]=y;
            rank[y]+=rank[x];
        }
    }
private:
    int father[maxn];
    int rank[maxn];
} ufs;

int cmp(const void* a,const void* b)
{
    Edge aa=*(const Edge*)a, bb=*(const Edge*)b;
    return aa.w-bb.w;
}
void kruskal()
{
    int sumw=0,num=0;
    int u,v;
    ufs.makeset(n);
    for(int i=0; i<m; i++)
    {
        u=edges[i].u;
        v=edges[i].v;
        if(ufs.findset(u)!=ufs.findset(v))
        {
            printf("%d %d %d\n",u,v,edges[i].w);
            ufs.unionset(u,v);
            sumw+=edges[i].w;
            num++;
        }
        if(num>=n-1) break;
    }
    printf("weight of MST is %d\n",sumw);
}
int main()
{
    while(~scanf("%d%d",&n,&m))
    {
        for(int i=0; i<m; i++)
            scanf("%d%d%d",&edges[i].u,&edges[i].v,&edges[i].w);
        qsort(edges,m,sizeof(edges[0]),cmp);
        kruskal();
    }
    return 0;
}