from functools import reduce
# method one:字符串拼接
def method_one(a_list):
    num = "".join(map(str,a_list))
    return num

# method two:循环
def method_two(a_list):
    num = 0
    for i in a_list:
        num = num*10 + int(i)
    return num

# method three:Python内建的高阶函数
def method_three(a_list):
    num = reduce(lambda x,y: str(x) + str(y), a_list)
    return num

list = [1, 2, 3, 4, 5, 6, 7, 8, 9]
print(method_one(list))
print(method_two(list))
print(method_three(list))