HackerRank - Sherlock and the Valid String | Full solution with examples and visuals

Sherlock and the valid string is a programming challenge on HackerRank. A string is said to be valid if all the characters of the string appear the same number of times. It is also valid if one can remove any 1 character from the string and the remaining characters occur the same number of times.
Watch the video to understand the problem in a simplified manner. I then work along with you to solve it first using a Brute Force approach, and then an efficient approach. All along with visuals and explanations.

00:00 - Intro
01:12 - Problem Statement and Test Case
03:42 - Brute Force Solution
05:52 - Efficient Solution
10:36 - Dry-run of code
13:55 - Final thoughts

📚 Links I talk about in the video:

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[divyagupta]

i was trying to solve it by looking to geeks for geeks and many more site, but could not understood. Way you have explained is just commendable. Thank you so much

[surendharv]

Awesome Explanation sir.
I am very eager to see more videos on your problem solving

[amansharma-wwtv]

must say
really great explanation!!!!

[nilabhrabhattacharjee]

Wrong time complexity. In between you are sorting the array of frequencies. Best sorting algorithm will take O(NLog(N)) times at worst case. So, that will be dominant.

[chandrakumara]

very good Explanation and easy to understand

[buuzinta]

Did your complexity analysis account for the sort for both time and space?

[shantanu]

bhaiya mtbl gajab mindblowing, very impressive, zabardast

[jjoelthomas]

Can you please clarify why we need "first == 1" in if(first == 1 && second == last) return "YES". Because, with the previous condition, if(first == last), we will get to know that if first and last are matching. Now first is not matching. That's why we come to the second condition. At this point, first can have either 1 or 3. So checking first == 1, is it valid? I checked in HackerRun without "first==1" and it runs fine for all testcases

[srinivas]

Since we used Hashmap, I think the space will be O(n)?

[tusharchandra]

I agree with the others. You explained it very well.

[dineshchoudhary-yxun]

In which programming language sir r u explain

[gokulakannan]

Time complexity: O(n²) ?

Bcz, we sort the array

[anubhavnegi]

i nearly got it on my own, but didnt know how to traverse values in map associated to key in java.

[aniketroy]

I was trying to solve this Q only using strings and arrays...but I guess it is not possible, right? ( can we somehow do till the step where we receive an array "arr" with just using strings and arrays?)

[fagunraythatha]

Hello Sir, you have some great videos. But I have one question, as we use array.sort() : best time complexity that would give us is nlogn by quick sort. So, how is your whole solution is n??

[gopinath]

possible try to solve merge two sort array without extra space please its confusing

[sealovingsoura]

Please make a video on maximum palindrome hackerrank bcz there is no video in that no one can make me understand like u

[amansrivastava]

Bro, TC is O(n logn) you have sorted the array..

[himanshukrdiwedi]

Very nice but very less problem your Channel contain

[dineshchoudhary-yxun]

There are 18 errors in your code when i run in cpp language