algorithm: unique paths 2 (#1257)

* algorithm: add UniquePaths2 algo and a test for it

* fix: fix inaccuracies and spelling errors

Dynamic-Programming/tests/UniquePaths2.test.js

@@ -0,0 +1,19 @@
+import { uniquePaths2 } from '../UniquePaths2'
+
+describe('Unique Paths2', () => {
+  // Should return number of ways, taken into account the obstacles
+  test('There are obstacles in the way', () => {
+    expect(uniquePaths2([[0, 0, 0], [0, 1, 0], [0, 0, 0]])).toEqual(2)
+    expect(uniquePaths2([[0, 0, 0], [0, 1, 0], [0, 0, 0], [1, 0, 0]])).toEqual(3)
+  })
+  // Should return number of all possible ways to reach right-bottom corner
+  test('There are no obstacles in the way', () => {
+    expect(uniquePaths2([[0, 0, 0], [0, 0, 0], [0, 0, 0]])).toEqual(6)
+    expect(uniquePaths2([[0, 0, 0], [0, 0, 0]])).toEqual(3)
+  })
+  // Should throw an exception b/c input data has wrong type
+  test('There are wrong type of input data', () => {
+    expect(() => uniquePaths2('wrong input')).toThrow()
+    expect(() => uniquePaths2(100)).toThrow()
+  })
+})