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LongestPalindromeSubstring.java
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54 lines (42 loc) · 1.18 KB
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package Leetcode;
import java.util.Arrays;
import java.util.PriorityQueue;
import java.util.Scanner;
public class LongestPalindromeSubstring
{
public static void main( String[] args )
{
Scanner s = new Scanner( System.in );
String str =s.next();
System.out.println( longestPalindrome( str ) );
}
public static String longestPalindrome(String s) {
String longestPalindrome = "";
if(s==null || s.length()==0)
return longestPalindrome;
int len=0;
int start=0;
int end=0;
for(int i=0;i<s.length();i++)
{
int len1 = expandFromMiddle(s, i, i);
int len2 = expandFromMiddle(s, i, i+1);
len = Math.max(len1, len2);
if(len>end-start)
{
start = i-(len-1)/2;
end = i+len/2;
}
}
return s.substring(start,end);
}
private static int expandFromMiddle(String s, int i, int j)
{
while(i>= 0 && j <s.length() && s.charAt(i)==s.charAt(j))
{
i--;
j++;
}
return j-i+1;
}
}