LeetCode: Valid Palindrome

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" is not 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.

地址：https://oj.leetcode.com/problems/valid-palindrome/

算法：这道题应该可以直接上代码吧。

 1 class Solution { 2 public: 3     bool isPalindrome(string s) { 4         int n = s.size(); 5         int j = 0; 6         for(int i = 0; i < n; ++i){ 7             if(isalnum(s[i])){ 8                 s[j++] = tolower(s[i]); 9             }10         }11         s = s.substr(0,j);12         int len = j;13         j = j / 2;14         int i = 0;15         while(i < j && s[i] == s[len - i - 1])  ++i;16         return i == j;17     }18 };

LeetCode: Valid Palindrome