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
        mid=(low+high)//2
        if num==allist[mid]:
            print(mid)
            break
        elif num<=alist[mid]:
            high=mid-1
        elif high<low:
            print("没找到")
            break
        else:
            low=mid+1
binary_search(num,29)