leetcode Valid Palindrome 难度系数2 2.25

Question:

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.

public class Solution {
public boolean isPalindrome(String s) {
		if (s == null || s.length() == 0) {
			return true;
		}
		String sUsed = s.toLowerCase().trim();
		int left = 0;
		int right = sUsed.length() - 1;
		while (left < right) {
			if (!(sUsed.charAt(left) <= ‘z‘ && sUsed.charAt(left) >= ‘a‘)
					&& !(sUsed.charAt(left) <= ‘9‘ && sUsed.charAt(left) >= ‘0‘)) {
				++left;
			} else if (!(sUsed.charAt(right) <= ‘z‘ && sUsed.charAt(right) >= ‘a‘)
					&& !(sUsed.charAt(right) <= ‘9‘ && sUsed.charAt(right) >= ‘0‘)) {
				--right;
			} else if (sUsed.charAt(right) != sUsed.charAt(left)) {
				return false;
			} else if (sUsed.charAt(right) == sUsed.charAt(left)) {
				++left;
				--right;
			}

		}
		return true;
	}
}

leetcode Valid Palindrome 难度系数2 2.25

原文：http://blog.csdn.net/yiding_he/article/details/18840409