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Task/Greatest-common-divisor/Swift/greatest-common-divisor.swift

@@ -0,0 +1,36 @@
+// Iterative
+
+func gcd(var a: Int, var b: Int) -> Int {
+
+    a = abs(a); b = abs(b)
+
+    if (b > a) { swap(&a, &b) }
+
+    while (b > 0) { (a, b) = (b, a % b) }
+
+    return a
+}
+
+// Recursive
+
+func gcdr (var a: Int, var b: Int) -> Int {
+
+    a = abs(a); b = abs(b)
+
+    if (b > a) { swap(&a, &b) }
+
+    return gcd_rec(a,b)
+}
+
+
+private func gcd_rec(a: Int, b: Int) -> Int {
+
+    return b == 0 ? a : gcd_rec(b, a % b)
+}
+
+
+for (a,b) in [(1,1), (100, -10), (10, -100), (-36, -17), (27, 18), (30, -42)] {
+
+    println("Iterative: GCD of \(a) and \(b) is \(gcd(a, b))")
+    println("Recursive: GCD of \(a) and \(b) is \(gcdr(a, b))")
+}