aoc2021/Sources/10/10.swift

//
//  File.swift
//
//
//  Created by Max Nuding on 05.12.21.
//

import Foundation
import Runner
import Collections

struct Day10: Runnable {
    let inputPath: String
    
    public func run() {
        let input = try! String(contentsOfFile: inputPath)
        let lines = input
            .trimmingCharacters(in: .newlines)
            .components(separatedBy: .newlines)
            //.map { line in line.map { $0.wholeNumberValue! } }
        var s = Deque<String.Element>()
        var illegalCharacters = [String.Element]()
        for (lineNumber, line) in lines.enumerated() {
            for char in line {
                if char.isClosing {
                    if let popped = s.popFirst() {
                        if let shouldBeClosedBy = popped.closedBy {
                            if shouldBeClosedBy == char {
                                continue // Valid chunk
                            }
                            print("Line: \(lineNumber): Expected \(shouldBeClosedBy), but found \(char) instead")
                            illegalCharacters.append(char)
                            break
                        } else {
                            print("\(popped) should be an opening character, but cannot find a fitting closing char. Line: \(lineNumber+1), char: \(char)")
                        }
                    } else {
                        print("Found closing character \(char), but empty list!")
                    }
                }
                s.prepend(char)
            }
        }
        print(illegalCharacters.map{$0.score!}.reduce(0,+))
    }
    
    
}

extension String.Element {
    var isClosing: Bool { self == "]" || self == ")" || self == ">" || self == "}" }
    var closedBy: String.Element? {
        switch self {
        case "[":
            return "]"
        case "(":
            return ")"
        case "{":
            return "}"
        case "<":
            return ">"
        default:
            return nil
        }
    }
        
    var score: Int? {
        switch self {
        case ")":
            return 3
        case "]":
            return 57
        case "}":
            return 1197
        case ">":
            return 25137
        default:
            return nil
        }
    }
}