Leetcode: Same Tree 理解分析

/**
* Definition for binary tree
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
public class Solution {
public boolean isSameTree(TreeNode p, TreeNode q) {
if(p == null && q == null)  return true;
if(p == null || q == null)  return false;
if(p.val != q.val)  return false;
if(p.val == q.val) {
boolean res = isSameTree(p.left, q.left);
if(!res)    return false;
boolean re = isSameTree(p.right, q.right);
if(!re)    return false;
}
return true;
}
}