Python实现的归并排序算法示例

#-*- coding: UTF-8 -*-
import numpy as np
def Merge(a, f, m, l):
  i = f
  j = m + 1
  tmp = []
  while i <= m and j <= l:
    if a[i] <= a[j]:
      tmp.append(a[i])
      i += 1
    else:
      tmp.append(a[j])
      j += 1
  while i <= m:
    tmp.append(a[i])
    i += 1
  while j<= l:
    tmp.append(a[j])
    j+= 1
  i = f
  for x in xrange(0, len(tmp)):
    a[i] = tmp[x]
    i += 1
def MergeSort(a, f, l):
  if f< l:
    m = (l + f) / 2
    MergeSort(a, f, m)
    MergeSort(a, m+1, l)
    Merge(a, f, m, l)
if __name__ == '__main__':
  a = np.random.randint(0, 10, size = 10)
  print "Before sorting..."
  print "---------------------------------------------------------------"
  print a
  print "---------------------------------------------------------------"
  MergeSort(a, 0, a.size-1)
  print "After sorting..."
  print "---------------------------------------------------------------"
  print a
  print "---------------------------------------------------------------"