考前板子（常数怎么优化）

#pragma GCC optimize(3)
#include <bits/stdc++.h>
#define RE register
#define MAXN 210000
using namespace std;
inline int Read(){
    int x=0,f=1;char ch=getchar();
    while(!('0'<=ch&&ch<='9')){if(ch=='-')f=-f;ch=getchar();}
    while('0'<=ch&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
int fa[MAXN],cnt,so[MAXN];
long long ans;
int m,n,tot;
struct Saber{
	int from,to,wi;
}b[MAXN];
inline void add(int x,int y,int z){b[++cnt].from=x,b[cnt].to=y,b[cnt].wi=z;}
inline bool pai(int x,int y){return b[x].wi<b[y].wi;}
inline int found(int x){return fa[x]==x?x:found(fa[x]);}
int main(){
    n=Read();m=Read();
    for(RE int i=1;i<=m;i++){
        int x,y,z;
        x=Read(),y=Read(),z=Read();
        add(x,y,z);
    }
    for(RE int i=1;i<=n;i++)fa[i]=i;
    for(RE int i=1;i<=m;i++)so[i]=i;
    sort(so+1,so+m+1,pai);
    for(RE int i=1;i<=m;i++){
        int x=b[so[i]].from,y=b[so[i]].to;
        int f1=found(x),f2=found(y);
        if(f1!=f2){ans+=b[so[i]].wi;fa[f1]=fa[f2];}
    }
    printf("%d\n",ans);
    return 0;
}