1360. Number of Days Between Two Dates

class Solution:
    def daysBetweenDates(self, date1: str, date2: str) -> int:
        def isLeapYear(year: int) -> bool:
            return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)

        def daysInMonth(year: int, month: int) -> int:
            days = [
                31,
                28 + int(isLeapYear(year)),
                31,
                30,
                31,
                30,
                31,
                31,
                30,
                31,
                30,
                31,
            ]
            return days[month - 1]

        def calcDays(date: str) -> int:
            year, month, day = map(int, date.split("-"))
            days = 0
            for y in range(1971, year):
                days += 365 + int(isLeapYear(y))
            for m in range(1, month):
                days += daysInMonth(year, m)
            days += day
            return days

        return abs(calcDays(date1) - calcDays(date2))