52 lines
2.0 KiB
Swift
52 lines
2.0 KiB
Swift
import Foundation
|
|
|
|
func readInput(_ filePath: String) throws -> [[Character]] {
|
|
let content = try String(contentsOfFile: filePath, encoding: .ascii)
|
|
return content.split(separator: "\n").map(Array.init)
|
|
}
|
|
|
|
let XMAS: (Character, Character, Character, Character) = ("X", "M", "A", "S")
|
|
|
|
func dE(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return j < map[i].count - 3
|
|
&& (map[i][j], map[i][j+1], map[i][j+2], map[i][j+3]) == XMAS
|
|
}
|
|
func dW(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return j >= 3
|
|
&& (map[i][j], map[i][j-1], map[i][j-2], map[i][j-3]) == XMAS
|
|
}
|
|
func dS(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return i < map.count - 3
|
|
&& (map[i][j], map[i+1][j], map[i+2][j], map[i+3][j]) == XMAS
|
|
}
|
|
func dN(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return i >= 3
|
|
&& (map[i][j], map[i-1][j], map[i-2][j], map[i-3][j]) == XMAS
|
|
}
|
|
func dNW(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return i >= 3 && j >= 3
|
|
&& (map[i][j], map[i-1][j-1], map[i-2][j-2], map[i-3][j-3]) == XMAS
|
|
}
|
|
func dSE(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return i < map.count - 3 && j < map[i].count - 3
|
|
&& (map[i][j], map[i+1][j+1], map[i+2][j+2], map[i+3][j+3]) == XMAS
|
|
}
|
|
func dNE(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return i >= 3 && j < map[i].count - 3
|
|
&& (map[i][j], map[i-1][j+1], map[i-2][j+2], map[i-3][j+3]) == XMAS
|
|
}
|
|
func dSW(_ map: [[Character]], _ i: Int, _ j: Int) -> Bool {
|
|
return i < map.count - 3 && j >= 3
|
|
&& (map[i][j], map[i+1][j-1], map[i+2][j-2], map[i+3][j-3]) == XMAS
|
|
}
|
|
|
|
func xmasCount(_ map: [[Character]], _ i: Int, _ j: Int) -> Int {
|
|
let funcs = [dE, dW, dS, dN, dNW, dSE, dNE, dSW]
|
|
return funcs.reduce(0, { sum, f in f(map, i, j) ? sum+1 : sum })
|
|
}
|
|
|
|
let input = try readInput(CommandLine.arguments[1])
|
|
let answer = (0..<input.count).reduce(0, { n, i in n +
|
|
(0..<input[i].count).reduce(0, { n, j in n + xmasCount(input, i, j) }) })
|
|
print(answer)
|