input: Write a function to find the length of the longest subarray that contains equal number of 1s and 0s.
  assert find_longest_subarray_length([1, 0, 1, 0, 1, 1, 0]) == 4
  assert find_longest_subarray_length([1, 1, 1, 0, 0, 0, 1, 0]) == 6
  assert find_longest_subarray_length([1, 0, 1, 1, 0, 0, 1, 1, 0]) == 8
output: def find_longest_subarray_length(arr):
      max_len = 0
      count = 0
      count_map = {0: -1}
  
      for i in range(len(arr)):
          count += 1 if arr[i] == 1 else -1
  
          if count in count_map:
              max_len = max(max_len, i - count_map[count])
          else:
              count_map[count] = i
  
      return max_len