aoc2021/Sources/09/09.swift

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2021-12-09 06:35:17 +00:00
//
// File.swift
//
//
// Created by Max Nuding on 05.12.21.
//
import Foundation
import Runner
import Collections
struct Coord {
let row: Int
let col: Int
func getLeft() -> Coord? {
guard col > 0 else {
return nil
}
return Coord(row: row, col: col - 1)
}
func getRight() -> Coord { Coord(row: row, col: col + 1) }
func getAbove() -> Coord? {
guard row > 0 else {
return nil
}
return Coord(row: row - 1, col: col)
}
func getBelow() -> Coord { Coord(row: row + 1, col: col) }
}
struct Field {
let numbers: [[Int]]
let numCols: Int
let numRows: Int
init(numbers: [[Int]]) {
self.numbers = numbers
numCols = numbers.first!.count
numRows = numbers.count
}
func getNeighborsCoordsFor(coord: Coord) -> [Coord] {
return [coord.getAbove(), coord.getRight(), coord.getBelow(), coord.getLeft()]
.compactMap { $0 }
.filter { $0.row < numRows && $0.col < numCols }
}
func lowPointValueAt(coord: Coord) -> Int? {
let value = numbers[coord.row][coord.col]
return getNeighborsCoordsFor(coord: coord)
.map { numbers[$0.row][$0.col] }
.allSatisfy { $0 > value }
? value
: nil
}
}
struct Day09: Runnable {
let inputPath: String
func run() {
let input = try! String(contentsOfFile: inputPath)
let entries = input
.trimmingCharacters(in: .newlines)
.components(separatedBy: .newlines)
.map { line in line.map { $0.wholeNumberValue! } }
let field = Field(numbers: entries)
var sum = 0
for row in 0..<field.numRows {
for col in 0..<field.numCols {
if let lpv = field.lowPointValueAt(coord: Coord(row: row, col: col)) {
sum += lpv + 1
}
}
}
print(sum)
}
}