102 lines
3.0 KiB
Swift
102 lines
3.0 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 15s.12.21.
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//
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import Foundation
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import Runner
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import Collections
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typealias ThreatLevel = Int
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struct Coord: Hashable, CustomStringConvertible {
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let row: Int
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let col: Int
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var description: String { "(\(row), \(col))" }
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func neighbors() -> [Coord] {
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[
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Coord(row: row-1, col: col),
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Coord(row: row, col: col+1),
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Coord(row: row+1, col: col),
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Coord(row: row, col: col-1)
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]
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}
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}
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class Day15: Runnable {
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let inputPath: String
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var field = [Coord]()
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var lastRow: Int = 0
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var lastCol: Int = 0
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var parts = [[ThreatLevel]]()
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var neighbors = [Coord: [Coord]]()
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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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parts = input
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.trimmingCharacters(in: .newlines)
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.components(separatedBy: .newlines)
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.map { Array($0) }
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.map { ar in ar.map {c in ThreatLevel(c.description)!} }
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lastRow = parts.count - 1
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lastCol = (parts.first?.count ?? 0) - 1
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var unvisited = Set<Coord>()
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// Distances to startNode
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var totalThreatLevel = [Coord: ThreatLevel]()
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for row in parts.enumerated() {
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for col in row.element.indices {
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let c = Coord(row: row.offset, col: col)
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unvisited.insert(c)
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//totalThreatLevel[c] = Int.max
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}
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}
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let startNode = Coord(row: 0, col: 0)
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totalThreatLevel[startNode] = 0
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while let currentNode = unvisited.min(by: { totalThreatLevel[$0, default: Int.max] < totalThreatLevel[$1, default: Int.max] }) {
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//var currentNode = !
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unvisited.remove(currentNode)
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if neighbors[currentNode] == nil {
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neighbors[currentNode] = currentNode
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.neighbors()
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.filter {
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$0.col >= 0 && $0.col <= lastCol && $0.row >= 0 && $0.row <= lastRow
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}
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}
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var adjacent = neighbors[currentNode]!
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neighbors[currentNode] = adjacent
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adjacent = adjacent
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.filter {
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unvisited.contains($0)
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}
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let currentThreatLevel = totalThreatLevel[currentNode, default: Int.max]
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for a in adjacent {
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let testCost = parts[a] + currentThreatLevel
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if totalThreatLevel[a, default: Int.max] > testCost {
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totalThreatLevel[a] = testCost
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}
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}
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}
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print(totalThreatLevel[Coord(row: lastRow, col: lastCol)]!)
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}
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}
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extension Array where Element == Array<Int> {
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subscript(coord: Coord) -> Int {
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get { self[coord.row][coord.col] }
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set(newValue) {
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self[coord.row][coord.col] = newValue
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}
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}
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}
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