快速排序算法-python实现

#-*- coding: UTF-8 -*-
import numpy as np

def Partition(a, i, j):
    x = a[i]                                            #将数组的第一个元素作为初始基准位置
    p = i                                                #同时记录下该元素的位置
    while i < j:
        while i < j  and a[j] >= x:
            j -= 1
        while i < j and a[i] <= x:
            i += 1
        if i != j:
            a[i], a[j] = a[j], a[i]                 #交换a[i]与a[j]
    a[p], a[i] = a[i], a[p]                      #将a[p]与a[i]进行交换
    p = i                                              #得到分隔位置

    return p

def QuickSort(a, i, j):
    if i < j:
        p = Partition(a, i, j)
        QuickSort(a, i, p-1)
        QuickSort (a, p+1, j)

if __name__ == '__main__':

    a = np.random.randint(0, 100, size = 100)
    print "Before sorting..."

    print "---------------------------------------------------------------"
    print a
    print "---------------------------------------------------------------"
    QuickSort(a, 0, a.size - 1)
    print "After sorting..."
    print "---------------------------------------------------------------"
    print a
    print "---------------------------------------------------------------"