Problem URL: Day of the year

We can use the datetime module to convert the date to a datetime object and then use the timetuple method to get the day of the year.

import datetime

class Solution:
    def dayOfYear(self, date: str) -> int:
        Y, M, D = map(int, date.split('-'))
        return int((datetime.datetime(Y, M, D) - datetime.datetime(Y, 1, 1)).days + 1)

Time complexity: O(1)
Space complexity: O(1)

We can also use python's calendar module to get the day of the year.

import calendar

class Solution:
    def dayOfYear(self, date: str) -> int:
        def daysInAMonth(year: int, month: int) -> int:
            return calendar.monthrange(year, month)[1]

        year, month, day = map(int, date.split('-'))
        res = 0
        for mon in range(1, month):
            res += daysInAMonth(year, mon)

        return res + day

Time complexity: O(1)
Space complexity: O(1)