摘要：
Given a binary tree, return the bottom up level order traversal of its nodes' values. (ie, from left to right, level by level from leaf to root). For 阅读全文
摘要：
Given a binary tree, return the level order traversal of its nodes' values. (ie, from left to right, level by level). For example: Given binary tree [ 阅读全文
摘要：
Given a set of distinct integers, nums, return all possible subsets (the power set). Note: The solution set must not contain duplicate subsets. Exampl 阅读全文
摘要：
Given a 2D board and a word, find if the word exists in the grid. The word can be constructed from letters of sequentially adjacent cell, where "adjac 阅读全文
摘要：
Given a collection of distinct integers, return all possible permutations. Example: Input: [1,2,3] Output: [ [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1, 阅读全文