Create rotating-arrays-in-swift.swift

Author: vandadnp

source/rotating-arrays-in-swift.swift

@@ -0,0 +1,29 @@
+// Want to support my work 🤝? https://buymeacoffee.com/vandad
+
+extension Array {
+    private func timesToRotate(count: Int) -> Int? {
+        assert(count > 0)
+        assert(self.count > 1)
+        let times = count % self.count
+        return times > 0 ? times : nil
+    }
+    func rotatedLeft(count: Int) -> Self {
+        guard let times = timesToRotate(count: count) else { return self }
+        return Array(self[times...]) + Array(self[..<times])
+    }
+    func rotatedRight(count: Int) -> Self {
+        guard let times = timesToRotate(count: count) else { return self }
+        return Array(self.suffix(times)) + Array(self.prefix(self.count - times))
+    }
+}
+
+let arr = [1, 2, 3]
+
+assert(arr.rotatedLeft(count: 1) == [2, 3, 1])
+assert(arr.rotatedLeft(count: 3) == [1, 2, 3])
+assert(arr.rotatedLeft(count: 4) == [2, 3, 1])
+assert(arr.rotatedLeft(count: 8) == [3, 1, 2])
+
+assert(arr.rotatedRight(count: 2) == [2, 3, 1])
+assert(arr.rotatedRight(count: 1) == [3, 1, 2])
+assert(arr.rotatedRight(count: 5) == [2, 3, 1])