aoc2021/Sources/11/11.swift

//
//  File.swift
//
//
//  Created by Max Nuding on 11.12.21.
//

import Foundation
import Runner

struct Coord: Hashable {
    let row: Int
    let col: Int
    
    var left: Coord { Coord(row: row, col: col - 1) }
    var right: Coord { Coord(row: row, col: col + 1) }
    var top: Coord { Coord(row: row - 1, col: col) }
    var bottom: Coord { Coord(row: row + 1, col: col) }
    
    var topLeft: Coord { Coord(row: row - 1, col: col - 1) }
    var topRight: Coord { Coord(row: row - 1, col: col + 1) }
    var bottomLeft: Coord { Coord(row: row + 1, col: col - 1) }
    var bottomRight: Coord { Coord(row: row + 1, col: col + 1) }
    
    var neighbors: [Coord] {
        [topLeft, top, topRight, left, right, bottomLeft, bottom, bottomRight]
            .filter {coord in coord.col >= 0 && coord.col < 10 && coord.row >= 0 && coord.row < 10}
    }
}


class Day11: Runnable {
    let inputPath: String
    var octopuses = [[Int]]()
    var flashed = Set<Coord>()
    let numRows = 10
    let numCols = 10
    var numFlashes = 0
    
    required init(inputPath: String) {
        self.inputPath = inputPath
    }
    
    public func run() {
        let input = try! String(contentsOfFile: inputPath)
        octopuses = input
            .trimmingCharacters(in: .newlines)
            .components(separatedBy: .newlines)
            .map { Array($0) }
            .map { ar in ar.map {c in Int(c.description)!} }
         
        var step = 0
        while(flashed.count < numRows * numCols) {
            flashed = Set<Coord>()
            for row in octopuses.indices {
                for col in octopuses[row].indices {
                    octopuses[row][col] += 1
                }
            }
            for row in octopuses.indices {
                for col in octopuses[row].indices {
                    let coord = Coord(row: row, col: col)
                    checkAndFlash(at: coord)
                }
            }
            for flash in flashed {
                octopuses[flash] = 0
            }
            step += 1
            if step == 100 {
                print(numFlashes)
            }
        }
        print("All flashing at step: \(step)")
    }
    
    func checkAndFlash(at coord: Coord) {
        if octopuses[coord] <= 9 || flashed.contains(coord) {
            return
        }
        flashed.insert(coord)
        numFlashes += 1
        for neighbor in coord.neighbors.filter({!flashed.contains($0)}) {
            octopuses[neighbor] += 1
            checkAndFlash(at: neighbor)
        }
    }
}

extension Array where Element == Array<Int> {
    subscript(coord: Coord) -> Int {
        get { self[coord.row][coord.col] }
        set(newValue) {
            self[coord.row][coord.col] = newValue
        }
    }
    
    func fieldDescription(flashed: Set<Coord>) -> String {
        var desc = ""
        for row in indices {
            for col in self[row].indices {
                let c = flashed.contains(Coord(row: row, col: col)) ? " X" : String(format: "%02d", self[row][col])
                desc.append("\(c),")
            }
            desc.append("\n")
        }
        return desc
    }
}