《数据结构与算法Python语言描述》习题第二章第二题（python版）

ADT Date:                                  #定义日期对象的抽象数据类型
    Date(self, int year, int month, int day)   #构造表示year/month/day的对象
    difference(self, Date d2)                   #求出self和d2的日期差
    plus(self, int n)                           #计算出日期第self之后n天的日期
    num_date(self, int year, int n)             #计算year年第n天的日期
    adjust(self, int n)                         #将日期d调整n天（n为带符号整数）
    year(self)                                  #返回日期的年
    month(self)                                 #返回日期的月
    day(self)                                   #返回日期的天

 #!/usr/bin/env python
 # -*- coding:utf-8 -*-

 """
 ADT Date:                                       #定义日期对象的抽象数据类型
     Date(self, int year, int month, int day)    #构造表示year/month/day的对象
     difference(self, Date d2)                   #求出self和d2的日期差
     plus(self, int n)                           #计算出日期第self之后n天的日期
     num_date(self, int year, int n)             #计算year年第n天的日期
     adjust(self, int n)                         #将日期d调整n天（n为带符号整数）
     year(self)                                  #返回日期的年
     month(self)                                 #返回日期的月
     day(self)                                   #返回日期的天
 """

 class Date(object):
     __slots__ = ('_year', '_month', '_day')

     def __init__(self, year, month, day):
         if not isinstance(year, int) or not isinstance(month, int) or not isinstance(day, int):
             raise TypeError

         if 1800<=year<year+30:
             self._year = year
             if 1 <= month <= 12:
                 self._month = month
                 bigmonth = (1,3,4,7,8,10,12)
                 smallmonth = (4,6,9,11)
                 if month in bigmonth:
                     if 0<day<=31:
                         self._day = day
                     else:
                         raise ValueError("%d is not valid day!" % day)
                 if month in smallmonth:
                     if 0<day<=30:
                         self._day = day
                     else:
                         raise ValueError("%d is not valid day!" % day)
                 elif month == 2:
                     if Date.leap_year(year):
                         if 0<day<=29:
                             self._day = day
                         else:
                             raise ValueError("%d is not valid day!" % day)
                     else:
                         if 0<day<=28:
                             self._day = day
                         else:
                             raise ValueError("%d is not valid day,the year is not leap_year!" % day)
             else:
                 raise ValueError("%d is not valid month!" % month)
         else:
             raise ValueError("%d is not valid year!" % year)

     def difference(self, other):
         #日期差
         DateDiff = 0
         if self._year > other._year:
             #换个位置，方便计算
             tmp = (self._year,self._month,self._day)
             (self._year,self._month,self._day) = (other._year,other._month,other._day)
             (other._year, other._month, other._day) = tmp

         #两个年之间的年直接加它一年的天数，分闰年和非闰年区别366和365
         for i in range(self._year+1,other._year):
             if Date.leap_year(i):
                 DateDiff += 366
             else:
                 DateDiff += 365
         #比较小的年，用后面的月份的天数相加在加上该月剩余的天数
         for i in range(self._month+1, 13):
             DateDiff += Date.month_day(self._year,i)
         DateDiff += Date.month_day(self._year,self._month) - self._day

         #比较大的年，加前面月份的天数加上本月的天数
         for i in range(1,other._month):
             DateDiff += Date.month_day(other._year,i)
         DateDiff += other._day
         return DateDiff

     def plus(self,n):
         if not isinstance(n,int):
             raise TypeError
         if n<0:
             raise ValueError("%d is not valid,must >= 0" % n)
         self._day += n
         while self._day > Date.month_day(self._year,self._month):
             self._day -= Date.month_day(self._year,self._month)
             self._month += 1
             if self._month == 13:
                 self._month = 1
                 self._year += 1
         return Date(self._year, self._month, self._day)

     def num_date(self, year, n):
         if not isinstance(year, int) or not isinstance(n, int):
             raise TypeError
         if Date.leap_year(year):
             if n>366 and n<1:
                 raise ValueError
         else:
             if n>365 and n<1:
                 raise ValueError
         self._year = year
         #判该n对应的月份和天数
         for i in range(1,13):
             d = n
             n -= Date.month_day(year,i)
             if n<=0:
                 self._month = i
                 self._day = d
                 break
         return Date(self._year, self._month, self._day)

     def adjust(self,n):
         if not isinstance(n,int):
             raise TypeError
         #n为正的情况
         if n>=0:
             self.plus(n)
         #n为负的情况
         else:
             self._day += n
             while self._day < 0:
                 if self._month -1 == 0:
                     self._month = 13
                     self._year -= 1
                 self._day += Date.month_day(self._year, self._month-1)
                 self._month -= 1
         return Date(self._year, self._month, self._day)

     def __str__(self):
         return str(self._year) + "-" + str(self._month) + "-" + str(self._day)

     def year(self):
         return self._year

     def month(self):
         return self._month

     def day(self):
         return self._day

     @staticmethod
     def leap_year(year):
         if (year % 4 == 0 and year % 100 != 0) or year % 400 == 0:
             return True
         else:
             return False

     #每月的天数，字典实现
     @staticmethod
     def month_day(year,month):
         d = {}
         bigmonth = (1,3,5,7,8,10,12)
         smallmonth = (4,6,9,11)
         for i in range(1,13):
             if i in bigmonth:
                 d[i] = 31
             elif i in smallmonth:
                 d[i] = 30
             elif i == 2:
                 if Date.leap_year(year):
                     d[i] = 29
                 else:
                     d[i] = 28
         return d[month]

 if __name__=='__main__':
     d = Date(2003,12,10)
     d1 = Date(2005,2,28)
     print(d)
     print("===")
     print(d.difference(d1))
     d.plus(30)
     print("===")
     print(d)
     print("===")
     d3 = Date(2006,12,13)
     d3.num_date(2016,10)
     print(d3)
     d3.adjust(-20)
     print("===")
     print(d3)