摘要：
Given an array nums of n integers and an integer target, are there elements a, b, c, and d in nums such that a + b + c + d = target? Find all unique q 阅读全文
摘要：
Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. A mapping of digit to le 阅读全文
摘要：
Given an array nums of n integers and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the thr 阅读全文