Advent of Code 2020

These are my Advent of Code 2020 puzzle solutions and puzzle running tool. The solutions and tool are written in Swift and can be run as a command line tool on macOS or with the included Xcode project. The tool can optionally download and cache puzzle input from adventofcode.com or print private leaderboard statistics if a session cookie is provided.

Running Puzzles

Usage

USAGE: swift run AdventOfCode <puzzle-index> [--cookie <cookie>] [--test-input <test-input>] [--force-download]

OPTIONS:
  --cookie <cookie>       The cookie named "session" for adventofcode.com. Used to authenticate for downloading puzzle input. Optional if puzzle input is already stored in ./Input/<puzzle-index>.txt or
                          provided with --input. 
  --test-input <test-input>
                          An input string to test run the puzzle with. The input file will not be downloaded or read if test input is provided.
  --force-download        Force a download of puzzle input even if there's a local file cached. 

Example

$ swift run AdventOfCode 1 --cookie $AOC_COOKIE --force-download 

🗃 Preparing Input

Downloading input from https://adventofcode.com/2020/day/1/input
Downloaded 200 lines (988 chars) of input

🚀 Running AOC1

Part 1 Solution: 1009899 | ⏱ 24ms

Part 2 Solution: 44211152 | ⏱ 270ms

Viewing Leaderboard

The AdventOfCode tool can be used for viewing private leaderboard results, including the timestamp each user completed each part of a puzzle.

USAGE: swift run AdventOfCode view-leaderboard <leaderboard-id> [--puzzle-index <puzzle-index>] [--cookie <cookie>]

OPTIONS:
  --puzzle-index <puzzle-index>
                          The puzzle number to print statistics for. 
  --cookie <cookie>       The cookie named "session" for adventofcode.com. 

Example

$ swift run AdventOfCode view-leaderboard 976765 --cookie $AOC_COOKIE --puzzle-index 2

Day 2                 Part 1                Part 2
Peppermint Butler     12/01, 9:03:56 PM     12/01, 9:06:51 PM     
Princess Bubblegun    12/01, 9:06:14 PM     12/01, 9:14:29 PM     
Jake the Dog          12/01, 9:41:39 PM     12/01, 9:52:02 PM     
Finn the Human        12/01, 9:42:30 PM     12/01, 9:55:36 PM     
Marceline             12/03, 10:12:14 PM    12/03, 10:16:17 PM    
BMO                   Not Yet               Not Yet  

Retrieving Your Session Cookie

You will need to provide a session cookie to authenticate for downloading puzzle input or leaderboard stats. In Safari the cookie can be retrieved from Develop → Show Web Inspector → Storage.

You can store your session cookie in an environment variable to ease running puzzles (e.g. echo 'export AOC_COOKIE=<session-cookie>' >> ~/.zshenv).

Adding New Puzzles

1. Add a new struct in Sources/AdventOfCode/Puzzles that conforms to Puzzle and include in the AdventOfCode and AdventOfCodeTests targets in Xcode.
2. Update PuzzleSet.swift's puzzlesByIndex to map the puzzle index to the new struct.
3. Implement solve1(input:) and solve2(input:) to provide the puzzle solutions.

Testing

Unit tests for running puzzles with custom test input are available in PuzzleTests.swift. These can be run with the AdventOfCodeTests target.

Example

class AOCTests: XCTestCase {

    func testAOC1() {
        XCTAssertEqual(AOC1().solve1(input: "1721,979,366,299,675,1456"), 514579)
        XCTAssertEqual(AOC1().solve2(input: "1721,979,366,299,675,1456"), 241861950)
    }

}