prog13.java

//13. program to find the longest Palindrome Substring within a string
package chap3;

import java.util.Scanner;

public class prog13  
{ 
  
    static void printSubStr(String str, int low, int high)
    { 
        System.out.println(str.substring(low, high + 1)); 
    } 
  
 
    static int longestPalSubstr(String str) { 
        int n = str.length();    
  
       
        boolean table[][] = new boolean[n][n]; 
  
       
        int maxLength = 1; 
        for (int i = 0; i < n; ++i) 
            table[i][i] = true; 
  
       
        int start = 0; 
        for (int i = 0; i < n - 1; ++i) { 
            if (str.charAt(i) == str.charAt(i + 1)) { 
                table[i][i + 1] = true; 
                start = i; 
                maxLength = 2; 
            } 
        } 
          
    
        for (int k = 3; k <= n; ++k)
        { 
              
            for (int i = 0; i < n - k + 1; ++i)  
            { 
               
                int j = i + k - 1; 
  
           
                if (table[i + 1][j - 1] && str.charAt(i) ==  
                                          str.charAt(j)) { 
                    table[i][j] = true; 
  
                    if (k > maxLength) { 
                        start = i; 
                        maxLength = k; 
                    } 
                } 
            } 
        } 
        System.out.print("Longest palindrome substring is; "); 
        printSubStr(str, start, start + maxLength - 1); 
          
        return maxLength; 
    } 
  
    
    public static void main(String[] args) 
    { 
       Scanner sc = new Scanner (System.in);
        String str ; 
        System.out.println("Enter a String");
	    str =sc.nextLine();
        System.out.println("Length is: " + longestPalSubstr(str)); 
    } 
}