用Python实现的二分查找算法

#!/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:" 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))

</target:>

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

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!')