A functional quicksort

functional-quicksort.py

from random import randint

# Quicksort with starting index as pivot
def qsort(items):
  if len(items) < 2:
    return items
  pivot = items[0]
  left = list(filter(lambda x: x <= pivot, items[1:]))
  right = list(filter(lambda x: x > pivot, items[1:]))
  return qsort(left) + [pivot] + qsort(right)

# Quicksort implemented with a random pivot
def qsort(items):
  if len(items) < 2:
    return items
  p_i = randint(0, len(items) - 1)
  pivot = items[p_i]
  left = list(filter(lambda x: x <= pivot, items[:p_i] + items[p_i + 1:]))
  right = list(filter(lambda x: x > pivot, items[:p_i] + items[p_i + 1:]))
  return quicksort(left) + [pivot] + quicksort(right)