A happy string is defined as a string that:

• Consists only of characters from the set ['a', 'b', 'c'].

• Does not contain any two adjacent characters that are equal (that is, s[i] != s[i + 1] for all valid indices i).

Given two integers n and k, consider all happy strings of length n sorted in lexicographical order.

Return the $k^{ ext{th}}$ happy string of length n from this sorted list. If there are fewer than k happy strings of length n, return an empty string "".

Constraints:

• $1 \leq$ n $\leq 10$

• $1 \leq$ k $\leq 100$

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.