In principle the function does nothing other than building a binary-encoded path.
原则上，该函数只是建立一个二进制编码的路径。
Tip: This function is binary safe.
提示：这个函数是二进制精确的。
Note: This function is binary safe.
注意：这个函数是二进制精确的。
Write a function to find the depth of a binary tree.
写个程序找到一个二叉树的深度。
Given two binary trees, write a function to check if they are equal or not.
题目大意：给定两个二叉树，判断两者是否是相同的二叉树。即结构相同且对应节点的值也相同。
Given two binary trees, write a function to check if they are equal or not.
题目大意：给定两个二叉树，判断两者是否是相同的二叉树。即结构相同且对应节点的值也相同。
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