Problem
Return the number of days in month of year in the Gregorian calendar. February has 29 days in a leap year: years divisible by 4, except those divisible by 100 unless also divisible by 400. A helper function is_leap(year) keeps the code tidy.
Implement days_in_month(year, month).
Input
year: The year. month: The month, 1 (January) to 12 (December).
Output
Return the number of days.
Constraints
1 ≤ year ≤ 9,999; 1 ≤ month ≤ 12
Examples
Input:
year = 2024
month = 2
Expected output:
expected = 29Input:
long long year = 2024;
long long month = 2;
Expected output:
long long expected = 29;Input:
long year = 2024;
long month = 2;
Expected output:
long expected = 29;Explanation
2024 is divisible by 4 and not by 100, so it is a leap year: 29 days.
Input:
year = 1900
month = 2
Expected output:
expected = 28Input:
long long year = 1900;
long long month = 2;
Expected output:
long long expected = 28;Input:
long year = 1900;
long month = 2;
Expected output:
long expected = 28;Explanation
1900 is divisible by 100 but not 400, so it is not a leap year: 28 days.
How to approach it
Try on your own first, then open one hint at a time.
Hint 1
Most months have a fixed day count; February depends on whether the year is leap.
Hint 2
Use a small lookup for month lengths, then adjust February with the leap-year rule.
Hint 3
Be careful with century years: divisible by 100 is not enough unless also divisible by 400.
Expected complexity
O(1) time, O(1) extra space
References
This challenge is adapted for CodeUtility. Follow the statement and constraints above.