input: Write a function to sort a given list of numbers in O(n) time complexity. The function should return the sorted list. If the input list is empty, it should return an empty list.
  
  assert sort_list([2, 6, 3, 8, 4])==[2, 3, 4, 6, 8]
  assert sort_list([])==[]
output: def sort_list(nums):
      if not nums:
          return []
      max_val = max(nums)
      count = [0] * (max_val + 1)
      for num in nums:
          count[num] += 1
      sorted_list = []
      for i in range(max_val + 1):
          sorted_list.extend([i] * count[i])
      return sorted_list