# To find all palindrome sub-strings using java

*Question*

Given a string find all the sub-strings which are palindrome and print those strings. A palindrome number is a number which is equal to its reverse. Even a single character is a palindrome.

*Logic*

- First, find all the sub-strings of the given string.
- Check each sub-string whether it is palindrome or not.
- If it is palindrome then print that string.

*Algorithm*

- We use substring function in java to get the sub-string and store that in a separate string. We have already covered how to find all the substrings
- Get the length of the sub-string and create a loop to check whether the respective characters are equal. First and the last character must be equal. Second first and second last must be equal and so on.
- If the sub-String satisfy the palindrome condition then print that string.

*Program*

class Substring { public static void main(String ar[]) { String str= "mamom"; int len = str.length(); int n,count=0; boolean flag= true; for(int i=0; i<len;i++) { for(int j=i+1;j<=len;j++) { /*To get substring from i to j-1*/ String sub = str.substring(i,j); flag = true; //reset flag n = sub.length()-1; /*loop to check whether the substring is palindrome*/ for(int k=0; k<sub.length()/2;k++,n--) { /*In string 'madam' we check * sub[0] == sub[4] * sub[1] == sub[3] * Both are true, so string is palindrome*/ if(sub.charAt(k) == sub.charAt(n)) continue; else { /*Condition for palindrome failed*/ flag =false; break; } } /*if the sub-string is palindrome(flag remains true)*/ if(flag) System.out.println(sub); } } } }

*Analysis*

Worst case time complexity is **O(n*n*n)**, here is n is the length of the string.

Space complexity is **O(1)**