Remove Palindromic Subsequences | Live Coding with Explanation | Leetcode - 1332

[@AlgorithmsMadeEasy]

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[@sudharshanchakravarthy7199]

What if the string is "baabbaaaba"? Good question by @bharat

[@MrACrazyHobo]

Oh my god I just realized - we are removing palindromic SUBSEQUENCES! NOT SUBSTRING! Thats how you can get a maximum of 2 as your answer
(remove all a's, then remove all b's)

[@AlgorithmsMadeEasy]

Rightly said!! 😊

[@phaniadityach2317]

can you please tell if there a way to find the number of ways in case of a string consisting of different characters? i.e, more than 2 distinct characters?

[@pironobcoding]

after seeing this solution my mind has been blown

[@AlgorithmsMadeEasy]

Thanks

[@bharatbhatia6000]

What if string is "baabbaaaba"
How will answer be 2 for this please explain.
I didn't get it

[@ForCodingInterview]

b'aabbaa'aba -> baba -> ""

[@bharatbhatia6000]

@@ForCodingInterview ok fine
But i still didn't get how the max result can be 2. Can you explain briefly

[@RahulGupta-qo7fi]

@@bharatbhatia6000 acc to Question, you can skip any number of character in string. As we have only 2 type a &b. So if we skip all a or all b , at max we have to do 2 steps. If all char are same means whole string is palindrome so , ans will be 1 . And in case of empty string, ans will be 0.

[@sudharshanchakravarthy7199]

@@ForCodingInterview how is "baba" a palindrome?

[@bharatbhatia6000]

@@sudharshanchakravarthy7199 yes good point..

[@hereweare644]

As you said 2 will be the maximum answer, but it doesn't suit for 'aababbaaba'. It takes 3 steps. If I was wrong please let me know.

[@AlgorithmsMadeEasy]

It will be maximum 2 because the question ask us to find subsequence.
Now the difference between substring and subsequence is that the substring is a continuous set of character while the same is not the case in subsequence. So i can just take all 'a' at once and then all 'b' the second time.
Hope it clears that up.

[@CRamPrasannaCV]

Understood :-)

[@bharathkalyans]

I approached this way, but could only pass 19/38 TC.🫡
private int solve(String s, int low, int high){
if(low > high) return s.length();
if(low == high) return 1;
if(low + 1 == high) return s.charAt(low) == s.charAt(high) ? 1 : 2;
if(s.charAt(low) == s.charAt(high))
return solve(s, low + 1, high - 1);
return Math.min(solve(s, low, high - 1), solve(s, low + 1, high)) + 1;
}