Python二分查找详解

#!/usr/bin/env python 
import sys  
 
def search2(a,m): 
  low = 0  
  high = len(a) - 1  
  while(low <= high): 
    mid = (low + high)/2 
    midval = a[mid] 
   
    if midval < m: 
      low = mid + 1  
    elif midval > m: 
      high = mid - 1  
    else: 
      print mid  
      return mid  
  print -1 
  return -1 
 
if __name__ == "__main__": 
  a = [int(i) for i in list(sys.argv[1])] 
  m = int(sys.argv[2]) 
  search2(a,m) 

administrator@ubuntu:~/Python$ python test_search2.py 123456789 4

class Solution(object):
  def searchRange(self, nums, target):
    """
    :type nums: List[int]
    :type target: int
    :rtype: List[int]
    """
    def binary_search(start,end,value):
      while end>=start:
        mid = (start+end)//2
        print(mid)
        if nums[mid]>target:
          end = mid-1
        elif nums[mid]<target:
          start = mid+1
        else: 
          if value==-1:
            if mid-1>=start and nums[mid+value] == target:
              end = mid+value
            else:
              return mid
          else:
            if mid+1<=end and nums[mid+value] == target:
              start = mid+value
            else:
              return mid
 
      return -1
    a=binary_search(0,len(nums)-1,-1)
    b=binary_search(0,len(nums)-1,1)
    return [a,b]
a = Solution()
l = [2,2]
print(a.searchRange(l,2))

import sys 
source = [1,2,3,4,5,6,7,8,9,10] #must be in order 
des = int(sys.argv[1]) 
low = 0 
high = len(source) - 1 
targetIndex = -1 
print "des=",des 
while low <= high: 
  middle = (low + high)/2 
  if des == source[middle]: 
    targetIndex = middle 
    break 
  elif des < source[middle]: 
    high = middle -1 
    print "middle element[index=",middle,",value=",source[middle],"] is bigger than des, continue search from[",low,"to",high,"]" 
  else: 
    low = middle + 1 
    print "middle element[index=",middle,",value=",source[middle],"] is smaller than des, continue search from[",low,"to",high,"]" 
print "search complete, target element's index in source list is ",targetIndex 

'fileName--BinarySearch.py' 
 
src = [] 
 
def BinarySearch(low, high, target, *src): 
  '二分查找' 
  while low <= high: 
    mid = (low + high) // 2 
    midVal = src[mid] 
    if target < midVal: 
      high = mid - 1 
    elif target > midVal: 
      low = mid + 1 
    else: 
      return mid 
    BinarySearch(low, high, target, *src) 
 
print('Please input 10 number:') 
for number in range(10): 
  src.append(int(input('Num %d:' % number))) 
 
sortList = tuple(src) 
 
key = int(input('Please input key:')) 
location = BinarySearch(0, len(src) - 1, key, *sortList) 
 
if location != None: 
  print('Find target at %d' % (location + 1)) 
else: 
  print('No target!')