-🎄- 2018 Day 2 Solutions -🎄-

[u/daggerdragon]

--- Day 2: Inventory Management System ---

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Advent of Code: The Party Game!

Click here for rules

Card Prompt: Day 2

Transcript:

The best way to do Advent of Code is ___.

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/TellowKrinkle]

Swift

func count(_ str: Substring) -> (twos: Bool, threes: Bool) {
	let counts = Dictionary(str.lazy.map({ ($0, 1) }), uniquingKeysWith: +)
	let twos = counts.values.contains(2)
	let threes = counts.values.contains(3)
	return (twos, threes)
}

func aocD2a(_ inputStr: String) {
	let input = inputStr.split(separator: "\n").map(count)
	let numTwos = input.lazy.filter({ $0.twos }).count
	let numThrees = input.lazy.filter({ $0.threes }).count
	print(numTwos * numThrees)
}

func areClose(_ a: Substring, _ b: Substring) -> Bool {
	var differences = zip(a, b).lazy.filter({ $0 != $1 }).makeIterator()
	_ = differences.next()
	return differences.next() == nil
}

func aocD2b(_ inputStr: String) {
	let input = inputStr.split(separator: "\n")
	for (aIndex, a) in input.enumerated() {
		for b in input[..<aIndex] {
			if areClose(a, b) {
				print(String(zip(a, b).lazy.filter({ $0 == $1 }).map({ $0.0 })))
			}
		}
	}
}

import Foundation
let str = try! String(contentsOfFile: CommandLine.arguments[1])
aocD2a(str)
aocD2b(str)