摘要：Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center). For example, this binary tree [1,2,2,3,4,4,3] is symmet 阅读全文

摘要：Given an array consisting of n integers, find the contiguous subarray of given length k that has the maximum average value. And you need to output the 阅读全文

摘要：题目： Given a non-empty 2D array grid of 0's and 1's, an island is a group of 1's (representing land) connected 4-directionally (horizontal or vertical. 阅读全文