d14

day14/d14p2.swift

@@ -0,0 +1,65 @@
+import Foundation
+
+let (w, h) = (101, 103)
+
+infix operator %%: MultiplicationPrecedence
+func %%<T: BinaryInteger>(lhs: T, rhs: T) -> T {
+    return (lhs % rhs + rhs) % rhs
+}
+
+struct Robot : CustomStringConvertible {
+    var (x, y): (Int, Int)
+    let (vx, vy): (Int, Int)
+    var description: String { return "p=(\(x), \(y)) v=(\(vx), \(vy))" }
+
+    mutating func move() {
+        x = (x + vx) %% w
+        y = (y + vy) %% h
+    }
+}
+
+func readInput(_ filePath: String) throws -> [Robot] {
+    let robot = try Regex(#"p=([0-9]+),([0-9]+) v=([0-9-]+),([0-9-]+)"#)
+    var robots: [Robot] = []
+    let content = try String(contentsOfFile: filePath, encoding: .ascii)
+    content.split(separator: "\n").forEach { line in
+        if let m = line.wholeMatch(of: robot) {
+            robots.append(Robot(
+                x: Int(m.output[1].substring!)!,
+                y: Int(m.output[2].substring!)!,
+                vx: Int(m.output[3].substring!)!,
+                vy: Int(m.output[4].substring!)!
+            ))
+        }
+    }
+    return robots
+}
+
+func complexity(_ input: String) -> Int {
+    var last: Character = " "
+    return input.reduce(0, { s, c in
+        if c != last { last = c; return s + 1 } else { return s }
+    })
+}
+
+func printRobots(_ robots: [Robot]) -> String {
+    var screen: [[String]] = Array(repeating: Array(repeating: " ", count: 101), count: 103)
+    robots.forEach { robot in screen[robot.y][robot.x] = "█" }
+    return screen.map { row in row.joined() }.joined(separator: "\n")
+}
+
+var bots = try readInput(CommandLine.arguments[1])
+var i = 0
+while true {
+    i += 1
+    for i in 0..<bots.count {
+        bots[i].move()
+    }
+    let printout = printRobots(bots)
+    let cpx = complexity(printout)
+    if cpx < 800 {
+        print(printout)
+        print("i=\(i) rle=\(cpx)")
+        break
+    }
+}