摘要：
Given a non-negative integernum, repeatedly add all its digits until the result has only one digit.For example:Givennum = 38, the process is like:3 + ... 阅读全文
摘要：
Given a binary tree, return all root-to-leaf paths.For example, given the following binary tree: 1 / \2 3 \ 5All root-to-leaf paths are:["1->... 阅读全文
摘要：
Given a binary tree, return thebottom-up level ordertraversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For exa... 阅读全文
摘要：
Given a binary tree, return thelevel ordertraversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary tree{3,9,2... 阅读全文