How Many Answers Are Wrong----hdu3038

#include<stdio.h>
#include<string.h>
#include<iostream>
#include<algorithm>
#include<math.h>
#define N 201000
#define INF 0xfffffff
using namespace std;

int f[N],vis[N],r[N];

int Find(int x)
{
    int k = f[x];
    if(x != f[x])
    {
        f[x] = Find(f[x]);
        r[x] += r[k];
    }
    return f[x];
}
int main()
{
    int px, py, ans, i, n, m, x, y, sum;
    while(scanf("%d%d", &n, &m)!=EOF)
    {
        for(i=0;i<=n;i++)
            f[i]=i,r[i]=0;
        ans = 0;
        while(m--)
        {
            scanf("%d%d%d", &x, &y, &sum);
            x --;
            px = Find(x);
            py = Find(y);
            if(px != py)
            {
                f[px] = py;
                r[px] = r[y] -r[x] - sum;
            }
            else if(r[y]-r[x] != sum)
                ans++;
        }
        printf("%d\n",ans);
    }
    return 0;
}