摘要：Encode and Decode TinyURL TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/design tinyurl and it return 阅读全文

摘要：454. 4Sum II Given four lists A, B, C, D of integer values, compute how many tuples (i, j, k, l) there are such that A[i] + B[j] + C[k] + D[l] is zero 阅读全文

摘要：two sum Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input would 阅读全文