最小生成树Kruscal算法

hihocoder1098

代码

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#include<vector>
using namespace std;
typedef long long ll;
const int maxn=1e6+7;
#define INF 0x3f3f3f3f
int fa[maxn];
int init(int n){
    for(int i=0;i<=n;i++)fa[i]=i;
}
int Find(int x){
    return fa[x]==x?x:fa[x]=Find(fa[x]);
}
int Union(int a,int b){
    int p1=Find(a),p2=Find(b);
    fa[p2]=p1;
}
struct edge{
    int from,to,val;
}Edge[maxn];
bool cmp(edge a,edge b){
    return a.val<b.val;
}
int n,m;
int main(){
    scanf("%d%d",&n,&m);
    init(n);
    for(int i=0;i<m;i++){
        scanf("%d%d%d",&Edge[i].from,&Edge[i].to,&Edge[i].val);
    }
    sort(Edge,Edge+m,cmp);
    int ans=0;
    for(int i=0;i<m;i++){
        if(Find(Edge[i].from)!=Find(Edge[i].to)){
            Union(Edge[i].from,Edge[i].to);
            ans+=Edge[i].val;
        }
    }
    printf("%d\n",ans);
    return 0;
}