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 "---------------------------------------------------------------"