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Remove Palindromic Subsequences

Updated: Mar 24, 2021

Given a string s consisting only of letters 'a' and 'b'. In a single step you can remove one palindromic subsequence from s.


Return the minimum number of steps to make the given string empty.


A string is a subsequence of a given string, if it is generated by deleting some characters of a given string without changing its order.


A string is called palindrome if is one that reads the same backward as well as forward.



Example 1:

Input: s = "ababa"
Output: 1
Explanation: String is already palindrome

Example 2:

Input: s = "abb"
Output: 2
Explanation: "abb" -> "bb" -> "". 
Remove palindromic subsequence "a" then "bb".

Example 3:

Input: s = "baabb"
Output: 2
Explanation: "baabb" -> "b" -> "". 
Remove palindromic subsequence "baab" then "b".

Constraints:

  • 1 <= s.length <= 1000

  • s[i] is either 'a' or 'b'.

Solution:



class Solution {
    public int removePalindromeSub(String s) {
        if(s.length()==0) return 0;
      StringBuilder sb=new StringBuilder(s);
    if(sb.reverse().toString().equals(s)) return 1;
        return 2;
    }
}



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