Greatest common divisor: Difference between revisions

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@@ Line 3,347: / Line 3,347: @@
 =={{header|Swift}}==
 <lang Swift>// Iterative
-func gcd(var a:Int, var b:Int) -> Int {
-    if (a < 0) {
+func gcd(var a: Int, var b: Int) -> Int {
-        a = -a
-    }
-    if (b < 0) {
-        b = -b
-    }
-    if (b > a) {
-        ( a, b ) = ( b, a )
-    }
-    while (true) {
+    a = abs(a); b = abs(b)
-        a %= b
-        if (a == 0) {
+    if (b > a) { swap(&a, &b) }
-            return b
-        }
+    while (b > 0) { (a, b) = (b, a % b) }
-        b %= a
+    return a
-        if (b == 0) {
-            return a
-        }
-    }
 }
 // Recursive
-func gcd_rec(a:Int, b:Int) -> Int {
-    if (b != 0) {
+func gcdr (var a: Int, var b: Int) -> Int {
-        return gcd_rec(b, a % b)
-    } else {
+    a = abs(a)
-        return 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))")
 }</lang>
+{{out}}
+<pre>
+Iterative: GCD of 1 and 1 is 1
+Recursive: GCD of 1 and 1 is 1
+Iterative: GCD of 100 and -10 is 10
+Recursive: GCD of 100 and -10 is 10
+Iterative: GCD of 10 and -100 is 10
+Recursive: GCD of 10 and -100 is 10
+Iterative: GCD of -36 and -17 is 1
+Recursive: GCD of -36 and -17 is 1
+Iterative: GCD of 27 and 18 is 9
+Recursive: GCD of 27 and 18 is 9
+Iterative: GCD of 30 and -42 is 6
+Recursive: GCD of 30 and -42 is 6
+</pre>
 =={{header|Tcl}}==