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