def binarysearch(names,x):
    left=0
    n=len(names)
    right=n
    while(left<=right):
        middle = (left+right) // 2
        if x == names[middle]:
            return 1
        elif x>names[middle]:
            left=middle+1
        else:
            right=middle
        return -1

name = [1,2,3,4]
if binarysearch(name,3) == 1:
    print("存在")

后记

middle = (left+right) // 2