python二分查找的原理分析

def binary_search(my_list, key):

    left = 0

    right = len(my_list)

    while left <= right:

        mid = (right - left) // 2

        if my_list[left + mid] < key:

            left = left + mid + 1

        elif my_list[left + mid] > key:

            right = left + mid - 1

        else:

            return left + mid

    return "None"

if __name__ == "__main__":

    my_list = [1, 3, 5, 7, 9, 11, 13]

    print("二分查找的原始数列：", my_list)

    print("二分查找的返回结果：", binary_search(my_list, 3))