摘要：
Remove the minimum number of invalid parentheses in order to make the input string valid. Return all possible results. Note: The input string may cont 阅读全文
摘要：
Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom. Example 阅读全文
摘要：
Given a binary tree containing digits from 0-9 only, each root-to-leaf path could represent a number. An example is the root-to-leaf path 1->2->3 whic 阅读全文
摘要：
Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any 阅读全文
摘要：
Given a binary tree, flatten it to a linked list in-place. For example, given the following tree: The flattened tree should look like: Approach #1: C+ 阅读全文