LeetCode编程练习 - Valid Palindrome学习心得

题目：

      Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

      For example,

      "A man, a plan, a canal: Panama"

is a palindrome.

      "race a car"

isnot
a palindrome.

      Note:
      Have you consider that the string might be empty? This is a good question to ask during an interview.

      For the purpose of this problem, we define empty string as valid palindrome.

   给定一个字符串，确定它是否是一个回文，只考虑忽略字母数字字符的情况。

思路：

   之前有遇到过判断回文的情况，只要判断前后字符是否相同就好，但这里，加了符号汉字，但原理还是一样的，定义两个指针，从开头和结尾开始遍历，遇到汉字或者符号就跳过，遇到字母数字就进行比较。查看解决方案。用IsDigit来判断数字，IsLetter判断字母。