快速排序算法

quicksort.py

实现一：
def quicksort(data):
	if len(data) < 2:
		return data
	pivot = data[1]
	less = [i for i in data[1:] if i <= pivot]
	greater = [i for i in data[1:] if i > pivot]
	return quicksort(less) + pivot + quicksort(greater)

实现二：
def quicksort(data, start, end):
	i = start
	j = end
	key = data[i]

	while i < j:
		while i < j and data[j] >= key:
			j = j - 1
		data[i] = data[j]
		while i < j and data[i] < key:
			i = i + 1
		data[j] = data[i]

	data[i] = key
	if i-1 > start:
		quicksort(data, start, i-1)
	if i+1 < end:
		quicksort(data, i+1, end)