75 lines
2.1 KiB
Swift
75 lines
2.1 KiB
Swift
//
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// File.swift
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//
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//
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// Created by Max Nuding on 14.12.21.
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//
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import Foundation
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import Runner
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struct Replacement {
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let from: String
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let to: String
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init(line: String) {
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let r = line.components(separatedBy: " -> ")
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from = r.first!
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to = r.last!
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}
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func replace(pair: String) -> String.Element? { pair == from ? to.first : nil }
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}
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class Day14: Runnable {
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let inputPath: String
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required init(inputPath: String) {
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self.inputPath = inputPath
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}
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public func run() {
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let input = try! String(contentsOfFile: inputPath)
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let parts = input
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.trimmingCharacters(in: .newlines)
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.components(separatedBy: "\n\n")
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var startingPolymer = parts.first!
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let replacements = parts.last!
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.components(separatedBy: .newlines)
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.map(Replacement.init)
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for step in 1...10 {
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var inserts = [(String.Index, Character)]()
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for i in startingPolymer.indices {
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let next = startingPolymer.index(i, offsetBy: 1)
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guard next != startingPolymer.endIndex else {
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continue
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}
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var pair = startingPolymer[i]/* + startingPolymer[next]*/
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let p = "\(startingPolymer[i])\(startingPolymer[next])"
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for replacement in replacements {
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if let c = replacement.replace(pair: p) {
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inserts.append((next, c))
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break
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}
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}
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}
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var tmp = startingPolymer
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var count = 0
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for r in inserts {
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let idx = tmp.index(r.0, offsetBy: count)
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tmp.insert(r.1, at: idx)
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count += 1
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}
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startingPolymer = tmp
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}
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let charCounts = startingPolymer.reduce(into: [String.Element: Int](), {
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$0[$1, default: 0] += 1
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})
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let maxC = charCounts.max(by: {$0.value < $1.value })!
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let minC = charCounts.min(by: {$0.value < $1.value })!
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print(maxC.value - minC.value)
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}
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}
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