摘要：
Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example,If n = 4 and k = 2, a solution is: 阅读全文
摘要：
The gray code is a binary numeral system where two successive values differ in only one bit. Given a non-negative integer n representing the total num 阅读全文
摘要：
Write a function to generate the generalized abbreviations of a word. Example: Given word = "word", return the following list (order does not matter): 阅读全文