LeetCode -- Same Tree

Question:

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

 

Analysis：

问题描述：给出两个二叉树，判断他们是否一致。如果他们结构相同并且每个节点的值都相等则两棵树一致。

思路：这种题目一看就是用递归，但是递归怎么用呢（大体是左边不空就返回左子树的判断，右边不空就返回右子树的判断）

 

Answer：

/**
 * Definition for a binary tree node.
 * 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 || p != null && q == null || p.val != q.val)
            return false;
        if(p != null && q != null)
            return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
        
        return true;
    }
}