#!/usr/bin/env python3 # -*- coding: utf-8 -*- def binaray_search(list, item): low = 0 high = len(list) - 1 i = 0 while(low <= high): mid = (low + high)/2 guess = mid if guess == item: i= i + 1 print('got it!') return guess,i elif guess < item: low = mid + 1 i= i + 1 else: high = mid - 1 i= i + 1 return 'no match', i if __name__ == '__main__': my_list = [1,2,3,4,5,6,7,8,9,10, 11,12] my_item = 13 a = binaray_search(my_list, my_item)[0] i= binaray_search(my_list, my_item)[1] print (i) if a == 'no match': print('no answer') else: print('to_fine_num is : %d, take %d times to find' %(a, i))
- 以上是python实现二分法搜索的代码,对于长度为2^n的list,最多需要n次即可确定目标,时间复杂度为O(logn).
- 前提:查找的list必须有序。