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IsPalindrome.java
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IsPalindrome.java
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public class IsPalindrome {
//Two pointer problem. One pointer to go from the beginning and one to go from the end.
//Every element selected by each pointer must match
//Unlike the longest palindrome problem, we can build in from the ends of the string because it is straightforward
//If you want to build out from the middle, you'll have to remove all the unwanted characters in the string, which would take time
public boolean isPalindrome(String s) {
s = s.trim();
if(s.length() == 0){
return true;
}
int pointer1 = 0;
int pointer2 = s.length() - 1;
while(pointer1 <= pointer2){
if(!Character.isLetterOrDigit(s.charAt(pointer1))){
pointer1++;
continue;
}
if(!Character.isLetterOrDigit(s.charAt(pointer2))){
pointer2--;
continue;
}
if(Character.toLowerCase(s.charAt(pointer1)) != Character.toLowerCase(s.charAt(pointer2))){
return false;
}else{
pointer1++;
pointer2--;
}
}
return true;
}
}