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### by Sumit Chourasia | May 03, 2020 | Category :coding | Tags : leetcodestringalgorithmआसानडेटा-संरचना

#### Remove Palindromic Subsequences Question with Solution. - मिनी टीवी

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 it is one that reads the same backward as well as forward.

Example 1:

``````Input: s = "ababa"

Output: 1

Explanation: String is already a 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".``````

Example 4:

``````Input: s = ""

Output: 0``````

Constraints:

``````0 <= s.length <= 1000

s only consists of letters 'a' and 'b'``````

Solution:

``````using System;
using System.Collections.Generic;
using System.Text;

{
class RemovePalindromeSubSol
{
public void execute()
{
var res = RemovePalindromeSub("ababa");
}
public int RemovePalindromeSub(string s)
{
if (s == null || s == "")
return 0;

for (int i = 0,j = s.Length - 1; i <= j; i++, j--)
{
if (s[i] != s[j])
return 2;
}
return 1;
}
}
}
``````

Time Complexity: O(n) - to check if the given string is palindrome or not in a single pass.

Space Complexity: O(1) - no extra space used.

Contributed By: Sumit Chourasia
Contributed By: Sumit Chourasia
Contributed By: Sumit Chourasia
Contributed By: Sumit Chourasia