HDU 3038 How Many Answers Are Wrong(种类并查集)

#include <cstring>
#include <cstdio>
#include <string>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
int o[200001];
int rank[200001];
int find(int x)
{
    if(x == o[x]) return x;
    int t = find(o[x]);
    rank[x] = rank[o[x]] + rank[x];
    return o[x] = t;
}
int main()
{
    int n,m,i,a,b,s,ans,x,y;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        for(i = 0;i <= n;i ++)
        {
            o[i] = i;
            rank[i] = 0;
        }
        ans = 0;
        for(i = 0;i < m;i ++)
        {
            scanf("%d%d%d",&x,&y,&s);
            x -- ;
            a = find(x);
            b = find(y);
            if(a != b)
            {
                o[a] = b;
                rank[a] = rank[y] - rank[x] + s;
            }
            else
            {
                if(rank[x] != rank[y] + s)
                ans ++;
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}