* Summary

Using [[https://adventofcode.com][Advent of Code]] as an excuse to learn some
Swift (so the code here won't be idiomatic, or polished; it's a repository for
exploring and understanding).

* Usage

~main.swift~ is configured to run the code for both day one and day two.  Can
run a single day by commenting out the unnecessary ones.

* Input data files

Input files are user-specific, so if you're not me, you'll need to update the
inputs in the ~Inputs~ directory.

There should be one file per day.  They can either be replaced in situ, or the
Xcode build settings can be tweaked to specify alternative files.

* Sample output

#+BEGIN_EXAMPLE
Day one:  5194970
Day two:  Part 1: 11590668 Part2 : 2254
#+END_EXAMPLE

* Swift resources

** General

1. [[https://swift.org/getting-started/][Swift getting started guide]]
2. [[https://docs.swift.org/swift-book/][The swift book]]
3. [[https://nshipster.com/swift-documentation/][Semi-official guide to docstrings in swift]]

** Swift linter in XCode:

1. [[https://github.com/realm/SwiftLint#xcode][SwiftLint]]

** References for particular days:

*** Day 4:

 1. Using an extension to split an int into an array of digits: [[https://www.hackingwithswift.com/example-code/language/how-to-split-an-integer-into-an-array-of-its-digits][from Hacking with Swift]]


* Notes for a day

** TODO [0/3] Day 5:

*** TODO Handle input
*** TODO Opcode 3: copies input to address (both increment instruction pointer by 2 not 4)
*** TODO Opcode 4: outputs value at address  (both increment instruction pointer by 2 not 4)