algorithm_fridays_week03.py

def binary_search(sorted_nums, val, minimum, maximum):
  if maximum < minimum:
    return -1

  mid = minimum + ((maximum - minimum) // 2)

  if val == sorted_nums[mid]:
    return mid
  elif val < sorted_nums[mid]:
    return binary_search(sorted_nums, val, minimum, mid - 1)
  else:
    return binary_search(sorted_nums, val, mid + 1, maximum)

def find_start_and_end_pos_of_val(nums, val):
  start = end = -1

  if nums == None or len(nums) == 0 or type(val) != int:
    return [start, end]

  sorted_nums = sorted(nums)
  val_index = binary_search(sorted_nums, val, 0, len(sorted_nums) - 1)

  if val_index == -1:
    return [start, end]

  start = end = val_index

  # Loop through downwards from the index below the value index
  for i in range(val_index - 1, -1, -1):
    if val == sorted_nums[i]:
      start = i
    else: break

  # Loop through upwards from the index above the value index
  for i in range(val_index + 1, len(sorted_nums)):
    if val == sorted_nums[i]:
      end = i
    else: break

  return [start, end]

if __name__ == '__main__':
  nums = [0, 8, -2, 5, 0]
  val = 0
  retval = find_start_and_end_pos_of_val(nums, val)
  print(retval)