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Python实现桶排序与快速排序算法结合应用示例

yipeiwu_com6年前 (2020-03-06)Python基础

本文实例讲述了Python实现桶排序与快速排序算法结合应用的方法。分享给大家供大家参考，具体如下：

#-*- coding: UTF-8 -*-
import numpy as np
from QuickSort import QuickSort
def BucketSort(a, n):
  barrel = {}
  for i in xrange(0,n):
    barrel.setdefault(i, [])
  min = np.min(a)
  max = np.max(a)
  for x in a:
    for i in xrange(0,n-1):
      if x >= min +i* (max - min)/n and x < min +(i +1) * (max - min)/n:
        barrel[i].append(x)
      elif i == n-2 and x >= min +(i +1) * (max - min)/n:
        barrel[i+1].append(x)
  k = 0
  for i in xrange(0,n):
    if len(barrel[i]) != 0:
      arr = np.array(barrel[i])
      QuickSort(arr, 0, len(barrel[i]) -1)
      for x in arr:
        a[k] = x
        k += 1
if __name__ == '__main__':
  a = np.random.randint(0, 100, size = 10)
  print "Before sorting..."
  print "---------------------------------------------------------------"
  print a
  print "---------------------------------------------------------------"
  BucketSort(a, 10)
  print "After sorting..."
  print "---------------------------------------------------------------"
  print a
  print "---------------------------------------------------------------"

快速排序QuickSort：

#-*- 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 "---------------------------------------------------------------"

程序运行结果：