def get_suffix(file_name):
    pos = file_name.rfind('.')
    if 0 < pos < len(file_name) - 1:
        return file_name[pos:]
    else:
        return ''

print(get_suffix('ddd.txt'))

总结：0 < pos < len(file_name) - 1是一种比较新奇的写法；截取字符串时省略后面的参数表示截取到字符串的最后

def get_max_2(li):
    m1, m2 = (li[0], li[1]) if li[0] > li[1] else (li[1], li[0])
    for i in range(2, len(li)):
        if li[i] > m1:
            m2 = m1
            m1 = li[i]
        elif li[i] > m2:
            m2 = li[i]
    return m1, m2

print(get_max_2([1, 2, 3, 4, 1000, 31, 43, 10000]))

总结：python可以给两个变量同时赋值，写法x1, x2 = list

#判断年份是否是闰年
def is_leap_year(year):
    return year % 4 == 0 and year % 100 != 0 or year % 400 == 0

#获取某日期是一年中的第几天
def get_day_index(year, month, date):
    days_of_month = [
        [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],
        [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
    ][is_leap_year(year)]
    total_days = 0
    for i in range(month - 1):
        total_days += days_of_month[i]
    total_days += date
    return total_days

print(get_day_index(2018, 2, 10))