摘要：
Given a binary tree, return all duplicate subtrees. For each kind of duplicate subtrees, you only need to return the root node of any one of them. Two 阅读全文
摘要：
We are given a binary tree (with root node root), a target node, and an integer value K. Return a list of the values of all nodes that have a distance 阅读全文
摘要：
Given an array of numbers, verify whether it is the correct preorder traversal sequence of a binary search tree. You may assume each number in the seq 阅读全文
摘要：
Determine whether two given binary trees are identical assuming any number of ‘tweak’s are allowed. A tweak is defined as a swap of the children of on 阅读全文