enhancement: FindLCM algorithm (TheAlgorithms#1222)

Co-authored-by: patrickwestervelt <pwestervelt3@gatech.edu>

Author: Psytew

Maths/FindLcm.js

@@ -11,16 +11,18 @@
 
 'use strict'
 
+import { findHCF } from './findHcf'
+
 // Find the LCM of two numbers.
 const findLcm = (num1, num2) => {
   // If the input numbers are less than 1 return an error message.
   if (num1 < 1 || num2 < 1) {
-    return 'Please enter values greater than zero.'
+    throw Error('Numbers must be positive.')
   }
 
   // If the input numbers are not integers return an error message.
   if (num1 !== Math.round(num1) || num2 !== Math.round(num2)) {
-    return 'Please enter whole numbers.'
+    throw Error('Numbers must be whole.')
   }
 
   // Get the larger number between the two
@@ -33,4 +35,19 @@ const findLcm = (num1, num2) => {
   }
 }
 
-export { findLcm }
+// Typically, but not always, more efficient
+const findLcmWithHcf = (num1, num2) => {
+  // If the input numbers are less than 1 return an error message.
+  if (num1 < 1 || num2 < 1) {
+    throw Error('Numbers must be positive.')
+  }
+
+  // If the input numbers are not integers return an error message.
+  if (num1 !== Math.round(num1) || num2 !== Math.round(num2)) {
+    throw Error('Numbers must be whole.')
+  }
+
+  return num1 * num2 / findHCF(num1, num2)
+}
+
+export { findLcm, findLcmWithHcf }

Maths/test/FindLcm.test.js

@@ -1,20 +1,39 @@
-import { findLcm } from '../FindLcm'
+import { findLcm, findLcmWithHcf } from '../FindLcm'
 
 describe('findLcm', () => {
   it('should throw a statement for values less than 1', () => {
-    expect(findLcm(0, 0)).toBe('Please enter values greater than zero.')
+    expect(() => { findLcm(0, 0) }).toThrow(Error)
   })
 
   it('should throw a statement for one value less than 1', () => {
-    expect(findLcm(1, 0)).toBe('Please enter values greater than zero.')
-    expect(findLcm(0, 1)).toBe('Please enter values greater than zero.')
+    expect(() => { findLcm(1, 0) }).toThrow(Error)
+    expect(() => { findLcm(0, 1) }).toThrow(Error)
   })
 
   it('should return an error for values non-integer values', () => {
-    expect(findLcm(4.564, 7.39)).toBe('Please enter whole numbers.')
+    expect(() => { findLcm(4.564, 7.39) }).toThrow(Error)
   })
 
   it('should return the LCM of two given integers', () => {
     expect(findLcm(27, 36)).toBe(108)
   })
 })
+
+describe('findLcmWithHcf', () => {
+  it('should throw a statement for values less than 1', () => {
+    expect(() => { findLcmWithHcf(0, 0) }).toThrow(Error)
+  })
+
+  it('should throw a statement for one value less than 1', () => {
+    expect(() => { findLcmWithHcf(1, 0) }).toThrow(Error)
+    expect(() => { findLcmWithHcf(0, 1) }).toThrow(Error)
+  })
+
+  it('should return an error for values non-integer values', () => {
+    expect(() => { findLcmWithHcf(4.564, 7.39) }).toThrow(Error)
+  })
+
+  it('should return the LCM of two given integers', () => {
+    expect(findLcmWithHcf(27, 36)).toBe(108)
+  })
+})