add Scala implementation for Euclidean (#427)

* add Scala example for Euclidean

* deal with negative args and zero

* deal with negative args and zero

* rename function

* change method name

* fix typo

Author: kenpower

contents/euclidean_algorithm/code/scala/euclidean.scala

@@ -0,0 +1,22 @@
+object Euclid {
+
+  def euclid_sub(a: Int, b: Int): Int =
+    (Math.abs(a), Math.abs(b)) match {
+      case (0, _) | (_, 0) => 0
+      case (x, y) if x < y => euclid(x, y - x)
+      case (x, y) if x > y => euclid(x - y, y)
+      case _ => a
+    }
+
+  def euclid_mod(a: Int, b: Int): Int =
+    (Math.abs(a), Math.abs(b)) match {
+      case (_, 0) => a
+      case (a, b) => euclid_mod(b, a % b)
+    }
+
+  def main(args: Array[String]): Unit = {
+    println(euclid_sub(151 * 899, 151 * 182))
+    println(euclid_mod(151 * 899, 151 * 182))
+  }
+
+}

contents/euclidean_algorithm/euclidean_algorithm.md

@@ -41,6 +41,8 @@ The algorithm is a simple way to find the *greatest common divisor* (GCD) of two
 [import:13-24, lang="nim"](code/nim/euclid_algorithm.nim)
 {% sample lang="f90" %}
 [import:1-19, lang="fortran"](code/fortran/euclidean.f90)
+{% sample lang="scala" %}
+[import:3-8, lang="scala"](code/scala/euclidean.scala)
 {% sample lang="racket" %}
 [import:3-14, lang="lisp"](code/racket/euclidean_algorithm.rkt)
 {% endmethod %}
@@ -90,6 +92,8 @@ Modern implementations, though, often use the modulus operator (%) like so
 [import:1-11, lang="nim"](code/nim/euclid_algorithm.nim)
 {% sample lang="f90" %}
 [import:21-34, lang="fortran"](code/fortran/euclidean.f90)
+{% sample lang="scala" %}
+[import:10-14, lang="scala"](code/scala/euclidean.scala)
 {% sample lang="racket" %}
 [import:16-24, lang="lisp"](code/racket/euclidean_algorithm.rkt)
 {% endmethod %}
@@ -144,6 +148,8 @@ The Euclidean Algorithm is truly fundamental to many other algorithms throughout
 [import, lang="nim" %](code/nim/euclid_algorithm.nim)
 {% sample lang="f90" %}
 [import, lang="fortran"](code/fortran/euclidean.f90)
+{% sample lang="scala" %}
+[import, lang="scala"](code/scala/euclidean.scala)
 {% sample lang="racket" %}
 [import, lang="lisp"](code/racket/euclidean_algorithm.rkt)
 {% endmethod %}