按照父亲表示法题解来打的,80pts

# include <stdio.h>
# include <iostream>

using namespace std;

int dad[1000001];
int nodecount;
int maxdeep=1;
int deep[1000001];

int Find(int node)
{
	if (deep[node] != 0) return deep[node] + 1;
	
	deep[node] = Find(dad[node]);
	
	return deep[node];
}

int main (void)
{
	scanf ("%d",&nodecount);
	
 	for (int i=1;i<=nodecount;i++) 
	{
		int a,b;
		scanf ("%d %d",&a,&b);
		dad[a] = dad[b] = i; 
	}
	
	deep[1] = 1;
	
	for (int i=2;i<=nodecount;i++) 
	{
		maxdeep = max(Find(i),maxdeep); 
	}
	

	printf("%d",maxdeep);
	
	return 0;
}

在递归这一段

int Find(int node)
{
	if (deep[node] != 0) return deep[node] + 1;
	
	deep[node] = Find(dad[node]);
	
	return deep[node];
}

将其改成题解中

int work(int x){	//递归函数，求节点 x 的深度
	if(depth[x]!=0)	//如果已经求出，就直接返回该深度
		return depth[x] ;
	if(fa[x]==0)
		return depth[x] = 1;
        			//根节点直接返回 1
	else
		return depth[x] = 1 + work(fa[x]);
        			//非根节点返回它的前驱节点的深度加 1
}

就能A，自认为两段代码等价，错在哪？