python 二分查找和快速排序实例详解

Z时代
2024-01-10
分类：综合

思想简单，细节颇多；本以为很简单的两个小程序，写起来发现bug频出，留此纪念。


#usr/bin/env python
def binary_search(lst,t):
  low=0
  height=len(lst)-1
  quicksort(lst,0,height)
  print lst
  while low<=height: 
    mid = (low+height)/2
    if lst[mid] == t:
      return lst[mid]
    elif lst[mid]>t:
      height=mid-1
    else:
      low=mid+1
  return -1
def quicksort( lst, left , right):
  low=left
  high=right
  key=lst[left]
  if left>=right:
    return 0
  while low<high:
    while low<high and key<lst[high]:
      high=high-1
    lst[low]=lst[high]
    while low<high and key>lst[low]:
      print lst[low]
      low=low+1
    lst[high]=lst[low]
    lst[low]=key
  quicksort( lst , left ,low-1)
  quicksort( lst , low+1 , right)
if __name__=='__main__':
  print binary_search([4,8,1,5,10,2,12,3,6,9],4)