二分查找

#二分查询
#有序列表
from asyncio.log import logger


def binary_search(arr,find):
    '''

    :param arr:
    :param find:
    :return:
    '''
    first = 0
    lasted = len(arr) - 1
    while first <= lasted:
        mid = (first+lasted)//2
        if arr[mid] == find:
            logger.debug("在mid处找到")
            return mid
        elif arr[mid] > find:
            lasted = mid-1
        elif arr[mid] < find:
            first = mid+1
    else:
        return -1


if __name__ == '__main__':
    arr_list = [1,3,7,9,99,101]
    find = int(input("请输入一个数字，查找是否在列表中"))
    res = binary_search(arr_list,find)
    print(res)

来源：https://blog.csdn.net/chuanying_xiaoqi/article/details/99456684