摘要：
Write a function to find the longest common prefix string amongst an array of strings. If there is no common prefix, return an empty string "". Exampl 阅读全文
摘要：
Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. Example 1: Example 2: 还是用DP来递归，抓住回 阅读全文