Advent of Code 2025 🎄

Welcome to my Advent of Code 2025 journey! This repository contains my solutions to the daily coding challenges from Advent of Code, an annual event where programming and problem-solving meet the holiday spirit.

About Advent of Code

Advent of Code is a series of daily programming puzzles released every December leading up to Christmas. Each puzzle offers a fun challenge, a chance to learn, and an opportunity to showcase problem-solving skills.

Structure

Each day's solutions are organized into individual directories:

📂 DayXX/
  ├── DayXX_<ProblemTitle>.md   # Problem solving approach
  ├── input.txt                 # Puzzle input (cached from AOC website after first run)
  ├── solution.py               # My Solution (python file)
  ├── solution_ai.py            # Vibe coded using AI to refactor & optimize my solution (Sometimes not so optimized)

Technologies Used

• Programming Language: Python 3.x
• Libraries:
  • requests - For fetching puzzle inputs from adventofcode.com
  • python-dotenv - For managing environment variables securely
  • pathlib - For cross-platform file path handling

Setup Instructions

1. Clone the repository:

git clone https://github.com/GKay-dev/Advent-Of-Code-2025.git
cd Advent-Of-Code-2025

2. Create and Activate Virtual Environment

# Create virtual environment
python -m venv venv

# Activate virtual environment
# On Linux/Mac:
source venv/bin/activate

# On Windows:
venv\Scripts\activate

3. Install Dependencies

pip install requests python-dotenv

4. Get Your Session Token

1. Log in to Advent of Code
2. Open browser DevTools (F12)
3. Go to Application → Cookies → https://adventofcode.com
4. Copy the value of the session cookie

5. Configure Environment Variables

Create a .env file in the repository root:

AOC_SESSION=your_session_token_here
AOC_YEAR=event_year  # AOC event year (event is happening since 2015)

Important: Never commit your .env file! It's already included in .gitignore.

6. Run Solutions

Run Individual Day Solutions

Navigate to a specific day's folder and run the solution:

cd DayXX                # Replace XX with day number (01-12)

python solution.py
# or
python solution_ai.py

Run All Solutions at Once

Execute all completed day solutions from the repository root:

python run_all.py

This will:

• Run both solution.py and solution_ai.py for each completed day
• Display timing information for each solution
• Save all output to AOC_2025_Output.txt
• Configure the number of days to run by modifying no_of_days variable in run_all.py

On first run, the script will automatically:

• Fetch your puzzle input from adventofcode.com
• Cache it to input.txt for subsequent runs

Technical Details

Input Handling System

• Automated Fetching: The aoc_utils.py module automatically fetches puzzle inputs using your session token
• Smart Caching: Inputs are cached locally to input.txt to avoid unnecessary web requests
• Flexible Options:
  • get_input(day=1) - Uses cache if available, otherwise fetches and saves
  • get_input(day=1, force_fetch=True) - Always fetches from web, overwrites cache
  • get_input(day=1, save_to_file=False) - Fetches but never saves to file

Timer Utility

• Performance Monitoring: The timer_utils.py module provides decorators for timing function execution
• Usage:

  @timer(name="Part One")
  def Part_One(input_data):
      # Your solution code
      pass
  
  # Time both parts together for cleaner output
  time_both_parts(Part_One, Part_Two, input_data)

Utility Functions

aoc_utils.py:

get_input(day, force_fetch=False, save_to_file=True)

• Handles fetching and caching puzzle inputs
• Automatically creates day directories if needed
• Returns input as string

timer_utils.py:

@timer(name="Timer Name")             # Decorator for timing individual functions (Timer name optional)
time_both_parts(func1, func2, *args)  # Time two functions with same arguments

run_all.py:

run_day(day_num)          # Execute both solution files for a specific day
run_all_days(no_of_days)  # Execute solutions for all days up to no_of_days

• Automatically discovers and runs all solution files in each day's directory
• Captures and redirects output to AOC_2025_Output.txt
• Provides timing information for individual days and overall execution

Modular Design

• aoc_utils.py contains reusable utilities for fetching inputs
• timer_utils.py provides performance measurement tools
• run_all.py orchestrates execution of all day solutions
• Each solution file is self-contained and can run independently
• Environment variables are loaded automatically via python-dotenv

Solution Variants

• solution.py: Original solution approach (No usage of AI in any manner)
• solution_ai.py: AI-optimized version with improved algorithms and performance enhancements (Sometimes, not so optimized)

Progress

Day	Part 1	Part 2
Day 1	✅	✅
Day 2	✅	✅
Day 3	✅	✅
Day 4	✅	✅
Day 5	✅	✅
Day 6	✅	✅
Day 7	✅	✅
Day 8	✅	✅
Day 9	✅	✅
Day 10	✅	✅
Day 11	✅	✅
Day 12	✅	✅

Feedback

Suggestions? Reach out via GitHub Issues.