HDU

题目连接：http://acm.hdu.edu.cn/showproblem.php?pid=3038

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<queue>
#include<stdlib.h>
#include<map>
#include<cmath>

using namespace std;

#define N 250000
#define INF 0x3f3f3f3f

int a[N], f[N];

int Find(int x)
{
    if(f[x] != x)
    {
        int p=f[x];
        f[x]=Find(f[x]);
        a[x]+=a[p];
    }
    return f[x];
}

int main()
{
   int m,n,i,b,c,s;

   while(scanf("%d%d", &n,&m) != EOF)
   {
       memset(a,0,sizeof(a));
       for(i=0;i<=n;i++)
        f[i]=i;

       int ans=0;
       for(i=0;i<m;i++)
       {
           scanf("%d%d%d", &b,&c,&s);
           b--;
           int x=Find(b);
           int y=Find(c);
           if(x != y)
           {
               f[y]=x;
               a[y]=a[b]+s-a[c];
           }
           else
           {
               if(a[c]-a[b] != s)
                ans++;
           }
       }
       printf("%d
", ans);
   }
   return 0;
}