Same Tree

题目地址：
https://leetcode.com/problems/same-tree/#/description

题目：

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.

解题思路：
这道题就是简单的dfs。

代码：

public boolean isSameTree(TreeNode p, TreeNode q) {
    if(p == null && q == null){
        return true;
    }
    if(p != null && q != null){
        if(p.val != q.val){
            return false;
        }
        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
    }
    return false;
}