[leedcode 100] Same Tree

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.

/**
 * 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) {
        //递归思想非常简单，首先判断根节点，然后分别判断左右节点
        //递归终止条件非常重要，必须同时为空
        if(p==null) return q==null;
        if(q==null) return false;
        if(p.val!=q.val)return false;
        return isSameTree(p.left,q.left)&&isSameTree(p.right,q.right);
    }
}