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https://leetcode.com/problems/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.
两个指针，一个指向头，一个指向尾。如果不是字母数字，就继续找，头++尾--，然后比较值就好啦。
没交的时候看到这道题有Solution，考虑了很久有没有其他机智的办法。等交了一看，其实并没有，一切都是错觉。
1 /** 2 * @param {string} s 3 * @return {boolean} 4 */ 5 var isPalindrome = function(s) { 6 s = s.trim(); 7 if(s === ""){ 8 return true; 9 }else{ 10 var i = 0, j = s.length - 1; 11 while(i <= j){ 12 while(!/[a-z0-9]/i.test(s[i]) && i < s.length && i < j){ 13 i++; 14 } 15 while(!/[a-z0-9]/i.test(s[j]) && j > 0 && i < j){ 16 j--; 17 } 18 19 if(s[i].toUpperCase() !== s[j].toUpperCase()){ 20 return false; 21 } 22 23 i++; j--; 24 } 25 26 i--; j++; 27 if(i !== j && s[i].toUpperCase() !== s[j].toUpperCase()){ 28 return false; 29 } 30 31 return true; 32 } 33 };
[LeetCode][JavaScript]Valid Palindrome
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原文地址：http://www.cnblogs.com/Liok3187/p/4512458.html
