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.
水题一道..
public class Solution {
public boolean isPalindrome(String s) {
int len = s.length();
if(len == 1 || len == 0) return true;
int h=0,t=len-1;
while (h < t){
if(!Character.isLetterOrDigit(s.charAt(h))){
h++;
}else if(!Character.isLetterOrDigit(s.charAt(t))){
t--;
}else if(Character.toLowerCase(s.charAt(h)) == Character.toLowerCase(s.charAt(t))){
t--;
h++;
}else{
return false;
}
}
return true;
}
}
