随机抽奖算法

题目：

从 1- n 中随机抽取 k 个数。

from random import randint

def sample(population, k):
    result = [None] * k
    pool = list(population)
    n = len(population)
    for i in range(k):
        j = randint(0, n-i)
        result[i] = pool[j]
        pool[j] = pool[n-i-1]  # 把末尾的元素移动到抽出的位置

    return result