最小生成树 模版

Posted 2020-10-03

//Gang
#include<iostream>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<cmath>
#define FOR(x,y,z) for(int x=y;x<=z;x++)
#define REP(x,y,z) for(int x=y;x>=z;x--)
#define ll long long
int n,m;
int fa[200005];
int find(int x)
{
    int p,temp;
    p=x;
    while(x!=fa[x])
    {
        x=fa[x];
    }
    while(x!=p)
    {
        temp=fa[p];
        fa[p]=x;
        p=temp;
    }
    return x;
}
struct node
{
    int x,y,z;
} e[200005];
int cmp(node a,node b)
{
    return a.z<b.z;
}
int tot=0;
int ans=0;
using namespace std;
int main()
{
    scanf("%d%d",&n,&m);
    FOR(i,1,n)
    fa[i]=i;
    FOR(i,1,m)
    scanf("%d%d%d",&e[i].x,&e[i].y,&e[i].z);
    sort(e+1,e+m+1,cmp);
    FOR(i,1,m)
    {
        int dx=find(e[i].x),dy=find(e[i].y);
        if(dx!=dy)
        {
            tot++;
            fa[dx]=dy;
            ans+=e[i].z;
        }
        if(tot==n-1)
        {
            printf("%d\n",ans);
            return 0;
        }
    }
    printf("orz\n");
    return 0;
}