摘要：
Given a singly linked list, determine if it is a palindrome.Follow up:Could you do it in O(n) time and O(1) space?判断一个链表是否为回文链表，有很多方法都可以进行判断，可以先遍历链表然后... 阅读全文
摘要：
Valid Palindrome Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. For example,"A man, a p 阅读全文
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Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999. 给定一个整数，将他转换到罗马字符。同样这里的罗马字符不会超过1000（M）,PS：关 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.首先是罗马字符串的特点：羅馬數字共有7個，即I（1）、V（5）、X（10）、L（50）、... 阅读全文