Given an array of integers digits, return the largest possible multiple of $3$ that can be formed by concatenating a subset of the given digits in any arrangement.

Return the result as a string. If no multiple of $3$ can be formed, return an empty string. The returned number must not contain leading zeros unless the value is $0$ itself.

Constraints:

• $1 \leq$ digits.length $\leq 10^4$

• $0 \leq$ digits[i] $\leq 9$

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.