Dynamic Programming - Longest Palindrome in a sequence

 package com.imaginea.dynamicprogramming;  
 import java.util.HashMap;  
 import java.util.Map;  
 /*  
  * Dynamic Programming implementation to get longest Palindrome in string sequence  
  * In order to solve a given problem, using a dynamic programming approach, we need to solve different parts of the problem (subproblems),   
  * then combine the solutions of the subproblems to reach an overall solution  
  * It is applicable to problems exhibiting the properties of 1. Optimal Substructure and 2. Overlapping Subproblem  
  * 1. Optimal Substructure: If optimal solution can be constructed efficiently from optimal solution of its subproblem.  
  * 2. Overlapping Subproblem: if the problem can be broken down into subproblem which are reused several times rather than to generate new subproblem.  
  *   
  * LP(i,j)     =1                    if i==j  
  *                =1                    if j=i+1 and x[i]!=x[j]  
  *                =2                     if j=i+1 and x[i]==x[j]  
  *                =LP(i+1, j-1)+2  
  *                =max(LP(i+1,j),LP(i,j-1))  
  */  

 public class LongestPalindromeSequence {  
      static Map<String, Integer> computedValues = new HashMap<String, Integer>();  
      public static void main(String[] args) {  
           int length = LP("BBABCBCAB");  
           System.out.println("Paliandrome Length::"+length);  
      }  
      private static int LP(String str){  
           if(computedValues.get(str)!= null){  
                return computedValues.get(str);  
           }  
           if(str.length()>0){  
                int i=0;  
                int j=str.length()-1;  
                if(i==j){  
                     return 1;  
                }else if(j == (i+1)){  
                     if(str.charAt(i)==str.charAt(j)){  
                          return 2;  
                     }else{  
                          return 1;  
                     }  
                }else if(str.charAt(i)==str.charAt(j)){  
                     int result = LP(str.substring(i+1, j))+2;  
                     computedValues.put(str,result);  
                     return result;  
                }else{  
                     int result = max(LP(str.substring(i+1, j+1)),LP(str.substring(i, j)));  
                     computedValues.put(str, result);  
                     return result;  
                }  
           }else{  
                System.out.println("Invalid String");  
                return -1;  
           }  
      }  
      private static int max(int n, int m){  
           if(n>m)  
                return n;  
           else  
                return m;  
      }  
 }