摘要：
Given a digit string excluded 01, return all possible letter combinations that the number could represent. A mapping of digit to letters (just like on 阅读全文
摘要：
Given a list of numbers with duplicate number in it. Find all unique permutations. Have you met this question in a real interview? Yes Given a list of 阅读全文
摘要：
Given a list of numbers, return all possible permutations. You can assume that there is no duplicate numbers in the list. Given a list of numbers, ret 阅读全文
摘要：
Given n friends, each one can remain single or can be paired up with some other friend. Each friend can be paired only once. Find out the total number 阅读全文