You are given a binary array nums containing only $0s$ and $1s$. Your task is to find the maximum length of a contiguous subarray in which the number of $0s$ and $1s$ is exactly equal.

Return the length of the longest such subarray.

Constraints:

• $1 \leq$ nums.length $\leq 10^5$

• nums[i] is either $0$ or $1$.

The solution utilizes a hash map and a running prefix count technique to determine the maximum length of a contiguous subarray with an equal number of $0s$ and $1s$ ...