代码：

def count1(list):

    x=0

    for i in range(0,len(list)):

        x=int(x)+int(list[i])

        avg=x/len(list)

    return int(avg)

def main(list):

    listfinal=[]

    while len(list)>1:

        listnew=[]

        for i in range(0,len(list)):

            # print(list[i],count1(list))

            if (list[i]>count1(list)):

                listnew.append(list[i])

            elif(list[i]==count1(list)):

                listnew.append(list[i])

                break

        list=listnew

    return list

if __name__ == '__main__':

    list=[2,3,4,7,9,12,33,19,19,33,33]

    print('列表',list,'的最大值是',main(list)[0],'。')

优化了下，增加主动输入的能力。

在主函数处，做了以下修改：
if __name__ == '__main__':

    # list=[2,3,4,7,9,12,33,19,19,33,1,12233]

    x = input('请输入整数列表（非整数会被取整）：')

    x = x.strip('[')

    x = x.strip(']')

    list1 = x.split(',')

    list1 = [float(list1[i]) for i in range(len(list1))]

    list2 = []

    for i in range(0,len(list1)):

        list2.append(int(list1[i]))

    print('输入的列表',list2,'的最大值是',main(list2)[0],'。')