二分查找算法

 

简单的二分查找算法

#!/usr/bin/env python
# coding:utf8
# author:Z time:2018/9/21

l = [2,3,5,10,15,16,18,22,26,30,32,35,41,42,43,55,56,66,67,69,72,76,82,83,88]

def func(l,aim):
    mid = (len(l)-1)//2#找到中间元素的索引
    if l:
        if aim > l[mid]:
            func(l[mid+1:],aim)#从中间元素的索引后面开始找
        elif aim < l[mid]:
            func(l[:mid],aim)#从中间元素的索引前面开始找
        elif aim == l[mid]:
            print("bingo",mid)
    else:
        print('找不到')

func(l,66)
func(l,6)

 

二分查找算法终极版

def search(num,l,start=None,end=None):
    start = start if start else 0
    end = len(l) if end is None else end
    mid = (end - start)//2 + start
    if start > end:
        return None
    elif l[mid] > num :
        return search(num,l,start,mid-1)
    elif l[mid] < num:
        return search(num,l,mid+1,end)
    elif l[mid] == num:
        return mid

print(search(83,l))