【剑指offer】面试题30：最小的K个数

import random

def partition(data, start, end):
	if  end <= start:
		return start
	index = random.randint(start, end)
	
	guard = data[index]
	
	while  True:
		while data[start] < guard: start += 1
		while data[end] > guard: end -= 1
		if start >= end: break
		data[start], data[end] = data[end], data[start]

	return start
			
def getKMins(data, k):
	if len( data ) <= k: return data
	start = 0; end = len( data ) - 1
	index = partition(data, start, end)
	while index != k - 1:
		if index > k - 1:
			index = partition(data, start, index - 1)
		else:
			index = partition(data, index + 1, end)
	return data[ 0 : k]