食物链

#include<iostream>  
#include<cstdio>  
#include<cstring>  
#include<algorithm>  
using namespace std;  
#define N 50010  
  
struct node  
{  
    int pre;  
    int relation;  
};  
node p[N];  
  
int find(int x) //查找根结点  
{  
    int temp;  
    if(x == p[x].pre)  
        return x;  
    temp = p[x].pre; //路径压缩  
    p[x].pre = find(temp);  
    p[x].relation = (p[x].relation + p[temp].relation) % 3; //关系域更新  
    return p[x].pre; //根结点  
}  
  
int main()  
{  
    int n, k;  
    int ope, a, b;  
    int root1, root2;  
    int sum = 0; //假话数量  
    scanf("%d%d", &n, &k);  
    for(int i = 1; i <= n; ++i) //初始化  
    {  
        p[i].pre = i;  
        p[i].relation = 0;  
    }  
    for(int i = 1; i <= k; ++i)  
    {  
        scanf("%d%d%d", &ope, &a, &b);  
        if(a > n || b > n) //条件2  
        {  
            sum++;  
            continue;  
        }  
        if(ope == 2 && a == b) //条件3  
        {  
            sum++;  
            continue;  
        }  
        root1 = find(a);  
        root2 = find(b);  
        if(root1 != root2) // 合并  
        {  
            p[root2].pre = root1;  
            p[root2].relation = (3 + (ope - 1) +p[a].relation - p[b].relation) % 3; //举例推公式 
        }  
        else  
        {  
            if(ope == 1 && p[a].relation != p[b].relation)  
            {  
                sum++;  
                continue;  
            }  
            if(ope == 2 && ((3 - p[a].relation + p[b].relation) % 3 != ope - 1))//观察得出  
            {  
                sum++;  
                continue;}  
        }  
    }  
    printf("%d\n", sum);  
    return 0;  
}