摘要：
1. Question Given n pairs of parentheses, write a function to generate all combinations of well formed parentheses. For example, given n = 3, a soluti 阅读全文
摘要：
1. Question Given an array S of n integers, are there elements a, b, c, and d in S such that a + b + c + d = target? Find all unique quadruplets in th 阅读全文
摘要：
1. Question Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives 阅读全文