📦 NEW: Added test cases for Project Euler Problem 15 and a minor bug …

…fix to the solution

Project-Euler/Problem015.js

@@ -7,8 +7,8 @@ How many such routes are there through a 20×20 grid?
 // A lattice path is composed of horizontal and vertical lines that pass through lattice points.
 
 export const latticePath = (gridSize) => {
-  let paths
-  for (let i = 1, paths = 1; i <= gridSize; i++) {
+  let paths = 1
+  for (let i = 1; i <= gridSize; i++) {
     paths = (paths * (gridSize + i)) / i
   }
   // The total number of paths can be found using the binomial coefficient (b+a)/a.

Project-Euler/test/Problem015.test.js

@@ -0,0 +1,13 @@
+import { expect } from 'vitest'
+import { latticePath } from '../Problem015'
+
+describe('Finding total numbers of Latice Paths', () => {
+  test.each([
+    [2, 6],
+    [4, 70],
+    [10, 184756],
+    [20, 137846528820]
+  ])('If Grid Size: %i, then Latice Paths count: %i', (a, expected) => {
+    expect(latticePath(a)).toBe(expected)
+  })
+})