Unroll matrix

DIRECTORY.md

@@ -170,6 +170,7 @@
   * [IsEven](Maths/IsEven.js)
   * [IsOdd](Maths/IsOdd.js)
   * [IsPronic](Maths/IsPronic.js)
+  * [JugglerSequence](Maths/JugglerSequence.js)
   * [LeapYear](Maths/LeapYear.js)
   * [LinearSieve](Maths/LinearSieve.js)
   * [LucasSeries](Maths/LucasSeries.js)
@@ -236,6 +237,7 @@
   * [Palindrome](Recursive/Palindrome.js)
   * [SubsequenceRecursive](Recursive/SubsequenceRecursive.js)
   * [TowerOfHanoi](Recursive/TowerOfHanoi.js)
+  * [UnrollMatrix](Recursive/UnrollMatrix.js)
 * **Search**
   * [BinarySearch](Search/BinarySearch.js)
   * [ExponentialSearch](Search/ExponentialSearch.js)

Recursive/UnrollMatrix.js

@@ -0,0 +1,35 @@
+/**
+ * @function UnrollMatrix
+ * @description Traverses/Unrolls array of arrays recursively until nothing is left.
+ * @param {Array} matrix - The input array of arrays
+ * @return {Array} matrix - The empty output array => [].
+ * @see https://chortle.ccsu.edu/vectorlessons/vmch13/vmch13_2.html
+ */
+
+const UnrollMatrix = (matrix) => {
+  if (matrix.length === 0) return matrix
+
+  // sweep top to right
+  if (matrix.length > 0) {
+    console.log(...matrix.shift())
+  }
+
+  // sweet top-right to bottom
+  if (matrix.length > 0) {
+    console.log(...matrix.map((arr) => arr.pop()))
+  }
+
+  // sweep bottom in reverse
+  if (matrix.length > 0) {
+    console.log(...matrix.reverse().pop())
+  }
+
+  // sweep bottom-left to top
+  if (matrix.length > 0) {
+    console.log(...matrix.map((arr) => arr.reverse().shift()))
+  }
+
+  return UnrollMatrix(matrix)
+}
+
+export { UnrollMatrix }

Recursive/test/UnrollMatrix.test.js

@@ -0,0 +1,52 @@
+import { UnrollMatrix } from '../UnrollMatrix'
+
+describe('UnrollMatrix', () => {
+  const emptyMatrix = [
+    []
+  ]
+
+  const evenMatrix = [
+    [1, 2, 3, 4],
+    [12, 13, 14, 5],
+    [11, 16, 15, 6],
+    [10, 9, 8, 7]
+  ]
+
+  const unevenMatrix = [
+    [1, 2, 3, 4],
+    [13, 14, 15, 16, 5],
+    [12, 18, 17, 6],
+    [11, 10, 9, 8, 7]
+  ]
+
+  const singleArrayMatrix = [
+    [1, 2, 3, 4]
+  ]
+
+  const deeplyNestedMatrix = [
+    [[[], [], [], [[], []]]],
+    [[[[], [], []], [[], []]]],
+    [[], [], [[], []], []],
+    [[], [], [], [], [[[], [], []]]]
+  ]
+
+  it('should return matrix length of 0 when given an empty matrix', () => {
+    expect(UnrollMatrix(emptyMatrix).length).toBe(0)
+  })
+
+  it('should return matrix length of 0 when given an even matrix', () => {
+    expect(UnrollMatrix(evenMatrix).length).toBe(0)
+  })
+
+  it('should return matrix length of 0 when given an uneven matrix', () => {
+    expect(UnrollMatrix(unevenMatrix).length).toBe(0)
+  })
+
+  it('should return matrix length of 0 when given a matrix with one array', () => {
+    expect(UnrollMatrix(singleArrayMatrix).length).toBe(0)
+  })
+
+  it('should return matrix length of 0 when given a deeply nested matrix', () => {
+    expect(UnrollMatrix(deeplyNestedMatrix).length).toBe(0)
+  })
+})