bzoj1202: [HNOI2005]狡猾的商人

/*************************************************************
Problem: bzoj 1202 [HNOI2005]狡猾的商人
User: fengyuan
Language: C++
Result: Accepted
Time: 224 ms
Memory: 1300 kb
Submit_Time: 2017-12-15 20:44:03
*************************************************************/

#include<bits/stdc++.h>
#define rep(i, x, y) for (int i = (x); i <= (y); i ++)
#define down(i, x, y) for (int i = (x); i >= (y); i --)
#define mid ((l+r)/2)
#define lc (o<<1)
#define rc (o<<1|1)
#define pb push_back
#define mp make_pair
#define PII pair<int, int>
#define F first
#define S second
#define B begin()
#define E end()
using namespace std;
typedef long long LL;
//head

const int N = 1005;
int n, m;
int fa
, sum
;

inline int getFa(int v)
{
if (fa[v] == v) return v;
int tmp = fa[v]; fa[v] = getFa(fa[v]);
sum[v] += sum[tmp];
return fa[v];
}

int main()
{
int Test; scanf("%d", &Test);
while (Test --){
scanf("%d%d", &n, &m); bool flag = true;
rep(i, 0, n) fa[i] = i, sum[i] = 0;
while (m --){
int x, y, z, fx, fy; scanf("%d%d%d", &x, &y, &z);
if (!flag) continue;
fx = getFa(-- x); fy = getFa(y);
if (fx != fy){
fa[fy] = fx; sum[fy] = sum[x] + z - sum[y];
} else if (sum[x]+z != sum[y]) flag = false;
} if (flag) puts("true"); else puts("false");
}
return 0;
}