Day Number of Year

Challenge Difficulty: Medium | Estimated completion time: ~20 minutes

You’re given a date string in the format month/day/year, based on the Gregorian calendar. Your task is to return which day of the year that date corresponds to (1–365, or 1–366 for leap years).

Examples

dayOfYear("12/13/2020")
output = 348
 
dayOfYear("11/16/2020")
output = 321
 
dayOfYear("1/9/2019")
output = 9
 
dayOfYear("3/1/2004")
output = 61
 
dayOfYear("12/31/2000")
output = 366 # leap year
 
dayOfYear("12/31/2019")
output = 365 # non leap year

Notes

• Make sure to account for leap years when February has 29 days.

Solution

Python

def day_of_year(date: str) -> int: """Calculate which day of the year a date is. Args: date: Date string in format "month/day/year" Returns: Day number of the year (1-365 or 1-366) """ month, day, year = map(int, date.split("/")) days_in_month = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] is_leap = (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0) if is_leap: days_in_month[1] = 29 day_number = sum(days_in_month[:month-1]) + day return day_number if __name__ == "__main__": print(day_of_year("12/13/2020")) # 348 print(day_of_year("11/16/2020")) # 321 print(day_of_year("1/9/2019")) # 9 print(day_of_year("3/1/2004")) # 61 print(day_of_year("12/31/2000")) # 366 print(day_of_year("12/31/2019")) # 365

Output