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Copy pathLongestPalindrome.java
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106 lines (82 loc) · 2.6 KB
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package LinkedInQuestions.Strings;
/**
* Created by rmukherj on 8/11/16.
*/
public class LongestPalindrome {
public String longestPalindrome(String str){
int start = 0, end=0;
for(int i=0;i<str.length();i++){
int len1 = expandAroundCenter(str,i,i);
int len2 = expandAroundCenter(str,i,i+1);
int len = Math.max(len1,len2);
if(len>end-start){
start = i-(len-1)/2;
end = i+(len/2);
}
}
return str.substring(start, end+1);
}
private int expandAroundCenter(String s, int left, int right){
while(left>=0&& right <s.length()&& s.charAt(left)== s.charAt(right)){
left--;
right++;
}
return left-right-1;
}
}
class LongestPalinderomeSubString{
private int lo, maxlen;
public String longestPalindromeSubString(String str){
int len = str.length();
if(len<2){
return str;
}
for(int i=0;i<len-1;i++){
extendPalindrome(str,i,i); // assume odd length, try to extend the palindrome as possible.
extendPalindrome(str,i,i+1); // assume even length.
}
return str.substring(lo, lo+maxlen);
}
private void extendPalindrome(String s, int left, int right){
while(left>=0&& right<s.length()&& s.charAt(left)==s.charAt(right)){
left--;
right++;
}
if(maxlen<right-left-1){
lo=left+1;
maxlen = right-left-1;
}
}
public static void main(String[] args) {
LongestPalinderomeSubString lps = new LongestPalinderomeSubString();
String str = "Rmanambiibiib";
String result = lps.longestPalindromeSubString(str);
System.out.println(result);
}
/*
public class PalindromeLongestSubstring{
int lo, maxlen;
public String palindromeLongestSubstring(String str){
int len = str.length();
if(len <2){
return str;
}
for(int i=0;i<len-1;i++){
expandPalindrome(str,i,i); //even
expandPalindrome(str, i, i+1); //odd
}
return str.substring(lo,lo+maxlen)
}
public void extendPalindrome(String s, int left, int right){
while(left>=0 && right<str.length&& str.charAt(left) n== str.charAt(right)){
left--;
right++;
}
if(maxlen<right-left-1){
lo=left+1;
maxlen= right-left-1;
}
}
}
*/
}