Add lcm.

src/algorithms/math/euclidean-algorithm/__test__/euclieanAlgorithm.test.js

@@ -20,5 +20,7 @@ describe('euclideanAlgorithm', () => {
     expect(euclideanAlgorithm(105, 252)).toBe(21);
     expect(euclideanAlgorithm(1071, 462)).toBe(21);
     expect(euclideanAlgorithm(462, 1071)).toBe(21);
+    expect(euclideanAlgorithm(462, -1071)).toBe(21);
+    expect(euclideanAlgorithm(-462, -1071)).toBe(21);
   });
 });

src/algorithms/math/euclidean-algorithm/euclideanAlgorithm.js

@@ -1,9 +1,12 @@
 /**
- * @param {number} a
- * @param {number} b
+ * @param {number} originalA
+ * @param {number} originalB
  * @return {number|null}
  */
-export default function euclideanAlgorithm(a, b) {
+export default function euclideanAlgorithm(originalA, originalB) {
+  const a = Math.abs(originalA);
+  const b = Math.abs(originalB);
+
   if (a === 0 && b === 0) {
     return null;
   }
@@ -16,9 +19,14 @@ export default function euclideanAlgorithm(a, b) {
     return a;
   }
 
+  // Normally we need to do subtraction (a - b) but to prevent
+  // recursion occurs to often we may shorten subtraction to (a % b).
+  // Since (a % b) is normally means that we've subtracted b from a
+  // many times until the difference became less then a.
+
   if (a > b) {
-    return euclideanAlgorithm(a - b, b);
+    return euclideanAlgorithm(a % b, b);
   }
 
-  return euclideanAlgorithm(b - a, a);
+  return euclideanAlgorithm(b % a, a);
 }