Advent of code 2021

This repository contains my personal solutions to Advent of code 2021.

All solutions are written in Python.

Things exercised during the days

• Days 1 and 2

  • Pytest
  • GitHub actions
  • map function

• Day 3

  • type hinting
  • from typing import List
  • zip function
  • bitwise xor ^
  • parsing binary numbers to decimals
  • pytest @fixture

• Day 4

  • zip function
  • transposing a matrix with zip function
  • flatmap with Python generators

• Day 5

  • named tuples

• Day 6

  • using pop to simulate a queue with a list

• Day 7

  • speeding up recurring calls to function by memoizing the results with @cache decorator

• Day 8

  • all sorts of set operations
  • iter and next

• Day 9

  • enumerate

• Days 10 and 11

  • regular expressions
  • using a dict with coordinates to represent two dimensional maps

• Day 12

  • Classes and objects
  • __str__ and __repr__

• Day 13

  • Thinking in terms of sets of coordinates and not two dimensional structures

• Day 14

  • First puzzle that I could not solve alone. Found a hint for part 2 from Koodiklinikka.
  • Using Counter to streamline counting character values

• Day 15

  • Using Dijkstra's Algorithm to find minimum travel cost between two points

• Day 16

  • Object oriented programming
  • Superclasses and subclasses
  • Overriding __len__ and __eq__
  • Creating generator functions with yield keyword

• Day 17

  • Object oriented programming

• Day 18

  • This was quite tricky
  • Using reduce to add all snail numbers together

• Day 19

  • This was again very difficult to solve...
  • Yielding lambdas

• Day 20

  • Working with infinite size images

• Day 21

  • Second puzzle where I could not solve part 2 alone. Found a hint 2 from Koodiklinikka.

• Day 22

  • Got a slow but working solution together after all.
  • Splitting a collection overlapping 3D cubes into non-overlapping ones until no cubes overlap.

• Day 23

  • Applying the shortest path logic to find the most efficient moves to solve a puzzle.

• Day 24

  • Iterative and recursive calls to a list of functions to keep and cache intermediate results.
  • Interpreting another languate into Python.

• Day 25

  • Wrapping a 2D plane over the horizontal and vertical axes.