my_search.py

import random

alist = []
for i in range(1, 101):
    alist.append(i)
num = random.choice(alist)
# 请完善二分查找函数binary_search(),查找出num在列表alist里面的索引位置

def binary_search(alist,num):
    low = 0
    high = len(alist) - 1
    while low <= high:
        mid = (low + high)//2
        if num == alist[mid]:
            return mid
        elif mid < num:
            low = mid + 1
        else:
            high = mid - 1
    return None

print("系统给的数是：",num)
print("它在列表里的索引是:",binary_search(alist,num))