Add flatten-array exercise (#274)

Author: keiravillekode

config.json

@@ -495,6 +495,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "flatten-array",
+        "name": "Flatten Array",
+        "uuid": "89db9aa8-83bd-4727-8eda-61de6b568690",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "flower-field",
         "name": "Flower Field",

exercises/practice/flatten-array/.docs/instructions.md

@@ -0,0 +1,16 @@
+# Instructions
+
+Take a nested array of any depth and return a fully flattened array.
+
+Note that some language tracks may include null-like values in the input array, and the way these values are represented varies by track.
+Such values should be excluded from the flattened array.
+
+Additionally, the input may be of a different data type and contain different types, depending on the track.
+
+Check the test suite for details.
+
+## Example
+
+input: `[1, [2, 6, null], [[null, [4]], 5]]`
+
+output: `[1, 2, 6, 4, 5]`

exercises/practice/flatten-array/.docs/introduction.md

@@ -0,0 +1,7 @@
+# Introduction
+
+A shipment of emergency supplies has arrived, but there's a problem.
+To protect from damage, the items — flashlights, first-aid kits, blankets — are packed inside boxes, and some of those boxes are nested several layers deep inside other boxes!
+
+To be prepared for an emergency, everything must be easily accessible in one box.
+Can you unpack all the supplies and place them into a single box, so they're ready when needed most?

exercises/practice/flatten-array/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "flatten-array.v"
+    ],
+    "test": [
+      "run_test.v"
+    ],
+    "example": [
+      ".meta/example.v"
+    ]
+  },
+  "blurb": "Take a nested list and return a single list with all values except nil/null.",
+  "source": "Interview Question",
+  "source_url": "https://reference.wolfram.com/language/ref/Flatten.html"
+}

exercises/practice/flatten-array/.meta/example.v

@@ -0,0 +1,33 @@
+module main
+
+type Box[T] = None | One[T] | Many[T]
+
+struct None {}
+
+struct One[T] {
+	value T
+}
+
+struct Many[T] {
+	boxes []Box[T]
+}
+
+fn flatten[T](box Box[T]) []T {
+	mut dest := []T{}
+	append(mut dest, box)
+	return dest
+}
+
+fn append[T](mut dest []T, box Box[T]) {
+	match box {
+		None {}
+		One[T] {
+			dest << box.value
+		}
+		Many[T] {
+			for element in box.boxes {
+				append(mut dest, element)
+			}
+		}
+	}
+}

exercises/practice/flatten-array/.meta/tests.toml

@@ -0,0 +1,56 @@
+# This is an auto-generated file. Regular comments will be removed when this
+# file is regenerated. Regenerating will not touch any manually added keys,
+# so comments can be added in a "comment" key.
+
+[8c71dabd-da60-422d-a290-4a571471fb14]
+description = "empty"
+
+[d268b919-963c-442d-9f07-82b93f1b518c]
+description = "no nesting"
+
+[3f15bede-c856-479e-bb71-1684b20c6a30]
+description = "flattens a nested array"
+
+[c84440cc-bb3a-48a6-862c-94cf23f2815d]
+description = "flattens array with just integers present"
+
+[d3d99d39-6be5-44f5-a31d-6037d92ba34f]
+description = "5 level nesting"
+
+[d572bdba-c127-43ed-bdcd-6222ac83d9f7]
+description = "6 level nesting"
+
+[0705a8e5-dc86-4cec-8909-150c5e54fa9c]
+description = "null values are omitted from the final result"
+
+[c6cf26de-8ccd-4410-84bd-b9efd88fd2bc]
+description = "consecutive null values at the front of the list are omitted from the final result"
+include = false
+
+[bc72da10-5f55-4ada-baf3-50e4da02ec8e]
+description = "consecutive null values at the front of the array are omitted from the final result"
+reimplements = "c6cf26de-8ccd-4410-84bd-b9efd88fd2bc"
+
+[382c5242-587e-4577-b8ce-a5fb51e385a1]
+description = "consecutive null values in the middle of the list are omitted from the final result"
+include = false
+
+[6991836d-0d9b-4703-80a0-3f1f23eb5981]
+description = "consecutive null values in the middle of the array are omitted from the final result"
+reimplements = "382c5242-587e-4577-b8ce-a5fb51e385a1"
+
+[ef1d4790-1b1e-4939-a179-51ace0829dbd]
+description = "6 level nest list with null values"
+include = false
+
+[dc90a09c-5376-449c-a7b3-c2d20d540069]
+description = "6 level nested array with null values"
+reimplements = "ef1d4790-1b1e-4939-a179-51ace0829dbd"
+
+[85721643-705a-4150-93ab-7ae398e2942d]
+description = "all values in nested list are null"
+include = false
+
+[51f5d9af-8f7f-4fb5-a156-69e8282cb275]
+description = "all values in nested array are null"
+reimplements = "85721643-705a-4150-93ab-7ae398e2942d"

exercises/practice/flatten-array/flatten-array.v

@@ -0,0 +1,17 @@
+module main
+
+type Box[T] = None | One[T] | Many[T]
+
+struct None {}
+
+struct One[T] {
+	value T
+}
+
+struct Many[T] {
+	boxes []Box[T]
+}
+
+fn flatten[T](box Box[T]) []T {
+	// Please implement the `flatten` function
+}