ACM模板

权值线段树：

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
const int maxn = 100007;
int f[maxn],d[maxn];
int n,m,l,r,v;
int find(int x)
{
    if(x==f[x])return x;
    int now = f[x];
    f[x]=find(f[x]);
    d[x]=d[x]+d[now];
    return f[x];
}
int main()
{
    scanf("%d %d",&n,&m);
    int ok = 1;
    for(int i=1;i<=n;i++)f[i]=i;
    for(int i=1;i<=m;i++)
    {
        scanf("%d %d %d",&l,&r,&v);
        int fl = find(l);
        int fr = find(r);
        if(fl==fr)
        {
            if(d[l]-d[r]!=v)ok = 0;
        }
        else
        {
            f[fl]=fr;
            d[fl]=v+d[r]-d[l];
        }
    }
    if(ok)cout<<"Yes"<<endl;
    else cout<<"No"<<endl;
    return 0;
}