RT， ::::info[提交记录] https://www.luogu.com.cn/record/227786431 ::::

::::info[代码]

#include<bits/stdc++.h>
#define int long long
using namespace std;
int fa[200005],d[200005],n;
int find(int x){
    if(x==fa[x]) return x;
    int fat=fa[x];
    fa[x]=find(fat);
    d[x]+=d[fat];
    return fa[x];
}
bool unit(int x,int y,int w){
    int rx=find(x),ry=find(y);
    if(rx==ry) return d[x]==d[y]+w;
    return fa[rx]=ry,d[rx]=d[y]+w-d[x];
}
bool solve(){
    int m,l,r,x;cin>>n>>m;
    for(int i=0;i<=n;i++) fa[i]=i,d[i]=0;
    while(m--){
        cin>>l>>r>>x;if(!unit(l-1,r,x)) return 0;
    }
    return 1;
}
signed main() {
    int T;cin>>T;
    while(T--) puts(solve()?"true":"false");
    return 0;
}

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