摘要：
题目描述: Given a collection of distinct numbers, return all possible permutations. For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], 阅读全文
摘要：
题目描述: Given an index k, return the kth row of the Pascal's triangle. For example, given k = 3,Return [1,3,3,1]. Note:Could you optimize your algorithm 阅读全文