d02

day02/d02p2.swift

@@ -0,0 +1,29 @@
+import Foundation
+
+func readInput(filePath: String) -> [[Int?]]? {
+    let content =  try? String(contentsOfFile: filePath, encoding: .ascii)
+    let lines = content?.split(separator: "\n")
+    return lines?.map { $0.split(separator: " ").map { Int($0) } }
+}
+
+func safe(_ report: [Int?]) -> Bool {
+    if report.contains(nil) {
+        return false
+    }
+    let diffs = zip(report.dropFirst(), report).map { $0.0! - $0.1! }
+    return diffs.allSatisfy { abs($0) >= 1 }
+        && diffs.allSatisfy { abs($0) <= 3 }
+        && (diffs.allSatisfy { $0 > 0 } || diffs.allSatisfy { 0 > $0 })
+}
+
+func drop<T>(_ l: [T], at: Int) -> [T] {
+    return l.enumerated().filter { $0.0 != at }.map { $0.1 }
+}
+
+func mutate<T>(_ l: [T]) -> [[T]] {
+    return (0..<l.count).map { drop(l, at: $0) }
+}
+
+let reports = readInput(filePath: CommandLine.arguments[1])
+let answer = reports!.map(mutate).filter { $0.contains(where: safe) }.count
+print(answer)