jpayne@68: package fun;
jpayne@68: 
jpayne@68: import shared.Tools;
jpayne@68: 
jpayne@68: public class Palindrome {
jpayne@68: 	
jpayne@68: 	public static void main(String[] args){
jpayne@68: 		System.out.println(longestPalindrome(args[0]));
jpayne@68: 	}
jpayne@68: 	
jpayne@68: 	public static String longestPalindrome(String s){
jpayne@68: 		int longestLength=0;
jpayne@68: 		int longestStart=0;
jpayne@68: 		for(int i=0; i<s.length(); i++){
jpayne@68: 			int lenEven=palindromeLength(s, i, i+1);
jpayne@68: 			if(lenEven>longestLength){
jpayne@68: 				longestLength=lenEven;
jpayne@68: 				longestStart=i-lenEven/2+1;
jpayne@68: 			}
jpayne@68: 			int lenOdd=palindromeLength(s, i, i);
jpayne@68: 			if(lenOdd>longestLength){
jpayne@68: 				longestLength=lenOdd;
jpayne@68: 				longestStart=i-lenOdd/2;
jpayne@68: 			}
jpayne@68: 		}
jpayne@68: 		return s.substring(longestStart, longestStart+longestLength+1);
jpayne@68: 	}
jpayne@68: 	
jpayne@68: 	public static int palindromeLengthOdd(String s, int middle){
jpayne@68: 		int length=1;
jpayne@68: 		int a=middle-1, b=middle+1;
jpayne@68: 		while(a>=0 && b<s.length()){
jpayne@68: 			if(s.charAt(a)==s.charAt(b)){
jpayne@68: 				a--;
jpayne@68: 				b++;
jpayne@68: 				length+=2;
jpayne@68: 			}else{
jpayne@68: 				break;
jpayne@68: 			}
jpayne@68: 		}
jpayne@68: 		return length;
jpayne@68: 	}
jpayne@68: 	
jpayne@68: 	public static int palindromeLengthEven(String s, int middle){
jpayne@68: 		int length=0;
jpayne@68: 		int a=middle, b=middle+1;
jpayne@68: 		while(a>=0 && b<s.length()){
jpayne@68: 			if(s.charAt(a)==s.charAt(b)){
jpayne@68: 				a--;
jpayne@68: 				b++;
jpayne@68: 				length+=2;
jpayne@68: 			}else{
jpayne@68: 				break;
jpayne@68: 			}
jpayne@68: 		}
jpayne@68: 		return length;
jpayne@68: 	}
jpayne@68: 	
jpayne@68: 	public static int palindromeLength(String s, int a, int b){
jpayne@68: 		while(a>=0 && b<s.length()){
jpayne@68: 			if(s.charAt(a)!=s.charAt(b)){break;}
jpayne@68: 			a--;
jpayne@68: 			b++;
jpayne@68: 		}
jpayne@68: 		return Tools.max(0, b-a-2);
jpayne@68: 	}
jpayne@68: 	
jpayne@68: 	public static boolean isPalindrome(String s, int a, int b){
jpayne@68: 		while(a<b){
jpayne@68: 			if(s.charAt(a)!=s.charAt(b)){
jpayne@68: 				return false;
jpayne@68: 			}
jpayne@68: 		}
jpayne@68: 		return true;
jpayne@68: 	}
jpayne@68: 	
jpayne@68: }