前段时间为准备百度面试恶补的东西，虽然最后还是被刷了，还是把那几天的“战利品”放点上来，算法一直是自己比较薄弱的地方，以后还要更加努力啊。
下面用python实现了几个常用的排序，如快速排序，选择排序，以及二路并归排序等等。
复制代码 代码如下:
#encoding=utf-8
import random
from copy import copydef directinsertsort(seq):
  直接插入排序
 size = len(seq)
 for i in range(1,size):
  tmp, j = seq[i], i
  while j > 0 and tmp    seq[j], j = seq[j-1], j-1
  seq[j] = tmp
 return seq
def directselectsort(seq):
  直接选择排序
 size = len(seq)
 for i in range(0,size - 1):
  k = i;j = i+1
  while j    if seq[j]     k = j
   j += 1
  seq[i],seq[k] = seq[k],seq[i]
 return seq
def bubblesort(seq):
 冒泡排序
 size = len(seq)
 for i in range(1,size):
  for j in range(0,size-i):
   if seq[j+1]     seq[j+1],seq[j] = seq[j],seq[j+1]
 return seq
def _divide(seq, low, high):
 快速排序划分函数
 tmp = seq[low]
 while low != high:
  while low = tmp: high -= 1
  if low    seq[low] = seq[high]
   low += 1
  while low   if low    seq[high] = seq[low]
   high -= 1
 seq[low] = tmp
 return low
def _quicksort(seq, low, high):
 快速排序辅助函数
 if low >= high: return
 mid = _divide(seq, low, high)
 _quicksort(seq, low, mid - 1)
 _quicksort(seq, mid + 1, high)
def quicksort(seq):
 快速排序包裹函数
 size = len(seq)
 _quicksort(seq, 0, size - 1)
 return seq
def merge(seq, left, mid, right):
 tmp = []
 i, j = left, mid
 while i   if seq[i]    tmp.append(seq[i])
   i += 1
  else:
   tmp.append(seq[j])
   j += 1
 if i  if j
 seq[left:right+1] = tmp[0:right-left+1]
def _mergesort(seq, left, right):
 if left == right:
  return
 else:
  mid = (left + right) / 2
  _mergesort(seq, left, mid)
  _mergesort(seq, mid + 1, right)
  merge(seq, left, mid+1, right)
#二路并归排序
def mergesort(seq):
 size = len(seq)
 _mergesort(seq, 0, size - 1)
 return seq
if __name__ == '__main__':
 s = [random.randint(0,100) for i in range(0,20)]
 print s
 print \n
 print directselectsort(copy(s))
 print directinsertsort(copy(s))
 print bubblesort(copy(s))
 print quicksort(copy(s))
 print mergesort(copy(s))
运行结果如下：
复制代码 代码如下:
e:\python_project\practice>sorting.py
[10, 47, 56, 76, 64, 84, 26, 8, 47, 51, 88, 81, 32, 95, 91, 29, 28, 69, 61, 45]
[8, 10, 26, 28, 29, 32, 45, 47, 47, 51, 56, 61, 64, 69, 76, 81, 84, 88, 91, 95]
[8, 10, 26, 28, 29, 32, 45, 47, 47, 51, 56, 61, 64, 69, 76, 81, 84, 88, 91, 95]
[8, 10, 26, 28, 29, 32, 45, 47, 47, 51, 56, 61, 64, 69, 76, 81, 84, 88, 91, 95]
[8, 10, 26, 28, 29, 32, 45, 47, 47, 51, 56, 61, 64, 69, 76, 81, 84, 88, 91, 95]
[8, 10, 26, 28, 29, 32, 45, 47, 47, 51, 56, 61, 64, 69, 76, 81, 84, 88, 91, 95]