[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.

public class Solution {
	public boolean isPalindrome(String s) {
		String str = s.toLowerCase();
		StringBuilder sb = new StringBuilder();
		StringBuilder rev = new StringBuilder();
		int i=0,j=s.length()-1;
		while(i<=j){
			while(i
  
   

正常遍历，提取有用的字符串，反序然后做比较。
   


   

   
public class Solution {
	public boolean isPalindrome(String s) {
		String str = s.toLowerCase();
		StringBuilder sb = new StringBuilder();
		StringBuilder rev = new StringBuilder();
		for(int i=0;i
    
     =0;i--){
			rev.append(sb.charAt(i));
		}
		if(sb.toString().equals(rev.toString())){
			return true;
		}
		return false;
	}
}