poj---1182---食物链

#include <cstdio>
#include <cstring>
#include <iostream>
#include <cmath>
#include<algorithm>
using namespace std;
 
const int maxn=100007;
const int INF=0x3f3f3f3f;
int father[maxn];
int val[maxn];
 
int Find(int x)
{
    if(father[x]==-1)return x;
    int tmp=Find(father[x]);
 
    val[x]+=val[father[x]];
    val[x]%=3;
    return father[x]=tmp;
}
 
int main()
{
    int n, m;
    scanf("%d %d", &n, &m);
 
    int ans=0;
    memset(father, -1, sizeof(father));
    memset(val, 0, sizeof(val));
 
    while(m--)
    {
        int D, x, y;
        scanf("%d %d %d", &D, &x, &y);
 
        if(x>n || y>n)
        {
            ans++;
            continue;
        }
 
        int a=Find(x);
        int b=Find(y);
        if(a==b)
        {
            if(D==1&&val[x]!=val[y])ans++;
            if(D==2&&(val[x]+1)%3!=val[y])ans++;
        }
 
        else
        {
            if(D==1)
            {
                father[b]=a;
                val[b]=val[x]-val[y];
                val[b]=(val[b]+3)%3;
            }
            else
            {
                father[b]=a;
                val[b]=val[x]-val[y]+1;
                val[b]=(val[b]+3)%3;
            }
        }
    }
    printf("%d\n", ans);
 
    return 0;
}