摘要：
A sequence of number is called arithmetic if it consists of at least three elements and if the difference between any two consecutive elements is the 阅读全文
摘要：
Given a sorted array consisting of only integers where every element appears twice except for one element which appears once. Find this single element 阅读全文
摘要：
Given a binary tree, return the tilt of the whole tree. The tilt of a tree node is defined as the absolute difference between the sum of all left subt 阅读全文