Given an integer num, return a string representing its base $7$ equivalent.

Constraints:

• $-10^7 \leq$ num $\leq 10^7$

The core idea behind this problem is standard base conversion using repeated division. To convert a decimal integer to its base $7$ representation, we repeatedly divide the number by $7$ and collect the remainders. Each remainder corresponds to a digit in the base $7$ result, starting from the least significant digit. After collecting all digits, we reverse their order to obtain the correct representation. We handle the sign separately by noting whether the original number is negative, working with its absolute value during conversion, and prepending a minus sign to the final result if needed. The special case of $0$ is handled upfront since the division loop would not execute for it.

Now, let’s look at the solution steps below:

1. If num equals ...