Counting number of days in a given month of a year
Detailed guide and Python implementation for the 'Counting number of days in a given month of a year' problem.
1. Concept Overview
The 'Counting number of days in a given month of a year' problem is a key challenge in the Numbers section.
This implementation focuses on easy-level logic in Python.
We prioritize technical accuracy and code readability in our provided solutions.
2. Real-World Applications
3. Visual Intuition
Visualizing the logic flow for Counting number of days in a given month of a year.
4. Prerequisites
5. Step-by-Step Thinking
1. Understand the problem
Read the problem statement for Counting number of days in a given month of a year carefully.
2. Formulate brute force
Draft a simple iterative solution.
3. Identify inefficiency
Look for redundant calculations.
4. Optimize search path
Use hashing or sorting to speed up the process.
5. Final Implementation
Clean up the code for production standards.
Problem Statement
Write a function days_in_month(month, year) that takes an integer month (1-12) and an integer year, and returns the number of days in that month.
Remember:
- Months with 31 days: January(1), March(3), May(5), July(7), August(8), October(10), December(12)
- Months with 30 days: April(4), June(6), September(9), November(11)
- February(2): 28 days normally, 29 days in a leap year
- Leap year: divisible by 4, but not by 100, unless also divisible by 400
- •1 <= month <= 12
- •1 <= year <= 9999
Examples
days_in_month(2, 2024)
29
2024 is divisible by 4 and not by 100, so it's a leap year. February has 29 days.
days_in_month(1, 2023)
31
January always has 31 days regardless of the year.
days_in_month(2, 1900)
28
1900 is divisible by 100 but not by 400, so it's NOT a leap year. February has 28 days.
Need a Hint?
Edge Cases to Watch
- Empty input structures
- Single element inputs
- Large numerical bounds
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Interview Insights & Variations
Complexity Analysis Breakdown
Why Time: Directly evaluates all possibilities.
Why Space: Uses standard local memory.
Why Time: Optimized paths reduce total operations.
Why Space: May trade memory for speed.
Optimized Solution Python Code
Optimized Solution Python Code
import calendar
def days_in_month_opt(month, year):
return calendar.monthrange(year, month)[1]Brute Force Code (Spoiler Guarded)
Brute Force Code (Spoiler Guarded)
def days_in_month_brute(month, year):
if month in [1, 3, 5, 7, 8, 10, 12]: return 31
if month in [4, 6, 9, 11]: return 30
if month == 2:
if (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0):
return 29
return 28
return 0Algorithm Pattern Checklist
When dealing with Numbers data patterns.
Core Prerequisites
Revision Key Notes
Common Mistakes & Pitfalls
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