摘要：
Given one stack with integers, sort it with two additional stacks (total 3 stacks). After sorting the original stack should contain the sorted integer 阅读全文
摘要：
Design a data structure that supports all following operations in average O(1) time. Note: Duplicate elements are allowed. Example: 380. Insert Delete 阅读全文
摘要：
Design a data structure that supports all following operations in average O(1) time. Example: insert, delete 用hashmap操作，get random用arraylist，map存<val, 阅读全文
摘要：
All DNA is composed of a series of nucleotides abbreviated as A, C, G, and T, for example: "ACGAATTCCG". When studying DNA, it is sometimes useful to 阅读全文
摘要：
TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/design-tinyurl and it returns a short URL such as http 阅读全文