摘要：
Description Write a function to find the longest common prefix string amongst an array of strings. 思路 最长的公共前缀，所以，先找出前两个的最长前缀，然后再和后面的比，在比的过程中，记录最小的串的长度 阅读全文
摘要：
Given a roman numeral, convert it to an integer.
Input is guaranteed to be within the range from 1 to 3999. 阅读全文
摘要：
Given an integer, convert it to a roman numeral.
Input is guaranteed to be within the range from 1 to 3999. 阅读全文