Data commit

Task/Farey-sequence/Swift/farey-sequence.swift

@@ -0,0 +1,49 @@
+class Farey {
+    let n: Int
+
+    init(_ x: Int) {
+        n = x
+    }
+
+    //using algorithm from wikipedia
+    var sequence: [(Int,Int)] {
+        var a = 0
+        var b = 1
+        var c = 1
+        var d = n
+        var results = [(a, b)]
+        while c <= n {
+            let k = (n + b) / d
+            let oldA = a
+            let oldB = b
+            a = c
+            b = d
+            c = k * c - oldA
+            d = k * d - oldB
+            results += [(a, b)]
+        }
+        return results
+    }
+
+    var formattedSequence: String {
+        var s = "\(n):"
+        for pair in sequence {
+            s += " \(pair.0)/\(pair.1)"
+        }
+        return s
+    }
+
+}
+
+print("Sequences\n")
+
+for n in 1...11 {
+    print(Farey(n).formattedSequence)
+}
+
+print("\nSequence Lengths\n")
+
+for n in 1...10 {
+    let m = n * 100
+    print("\(m): \(Farey(m).sequence.count)")
+}