Implemented the Binary Search Tree Exercise

config.json

@@ -409,6 +409,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "binary-search-tree",
+        "name": "Binary Search Tree",
+        "uuid": "52957e98-b5c5-46c7-a55c-d5e14a12652f",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "book-store",
         "name": "Book Store",

exercises/practice/binary-search-tree/.docs/instructions.md

@@ -0,0 +1,70 @@
+# Instructions
+
+Insert and search for numbers in a binary tree.
+
+When we need to represent sorted data, an array does not make a good data structure.
+
+Say we have the array `[1, 3, 4, 5]`, and we add 2 to it so it becomes `[1, 3, 4, 5, 2]`.
+Now we must sort the entire array again!
+We can improve on this by realizing that we only need to make space for the new item `[1, nil, 3, 4, 5]`, and then adding the item in the space we added.
+But this still requires us to shift many elements down by one.
+
+Binary Search Trees, however, can operate on sorted data much more efficiently.
+
+A binary search tree consists of a series of connected nodes.
+Each node contains a piece of data (e.g. the number 3), a variable named `left`, and a variable named `right`.
+The `left` and `right` variables point at `nil`, or other nodes.
+Since these other nodes in turn have other nodes beneath them, we say that the left and right variables are pointing at subtrees.
+All data in the left subtree is less than or equal to the current node's data, and all data in the right subtree is greater than the current node's data.
+
+For example, if we had a node containing the data 4, and we added the data 2, our tree would look like this:
+
+![A graph with root node 4 and a single child node 2.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2.svg)
+
+```text
+      4
+     /
+    2
+```
+
+If we then added 6, it would look like this:
+
+![A graph with root node 4 and two child nodes 2 and 6.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6.svg)
+
+```text
+      4
+     / \
+    2   6
+```
+
+If we then added 3, it would look like this
+
+![A graph with root node 4, two child nodes 2 and 6, and a grandchild node 3.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6-3.svg)
+
+```text
+       4
+     /   \
+    2     6
+     \
+      3
+```
+
+And if we then added 1, 5, and 7, it would look like this
+
+![A graph with root node 4, two child nodes 2 and 6, and four grandchild nodes 1, 3, 5 and 7.](https://assets.exercism.org/images/exercises/binary-search-tree/tree-4-2-6-1-3-5-7.svg)
+
+```text
+          4
+        /   \
+       /     \
+      2       6
+     / \     / \
+    1   3   5   7
+```
+
+## Credit
+
+The images were created by [habere-et-dispertire][habere-et-dispertire] using [PGF/TikZ][pgf-tikz] by Till Tantau.
+
+[habere-et-dispertire]: https://exercism.org/profiles/habere-et-dispertire
+[pgf-tikz]: https://en.wikipedia.org/wiki/PGF/TikZ

exercises/practice/binary-search-tree/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "rmonnet"
+  ],
+  "files": {
+    "solution": [
+      "binary_search_tree.odin"
+    ],
+    "test": [
+      "binary_search_tree_test.odin"
+    ],
+    "example": [
+      ".meta/example.odin"
+    ]
+  },
+  "blurb": "Insert and search for numbers in a binary tree.",
+  "source": "Josh Cheek"
+}

exercises/practice/binary-search-tree/.meta/example.odin

@@ -0,0 +1,48 @@
+package binary_search_tree
+
+Tree :: ^Node
+
+Node :: struct {
+	value: int,
+	left:  Tree,
+	right: Tree,
+}
+
+destroy_tree :: proc(t: Tree) {
+	if t == nil { return }
+	destroy_tree(t.left)
+	destroy_tree(t.right)
+	free(t)
+}
+
+insert :: proc(t: ^Tree, value: int) {
+
+	if t^ == nil {
+		t^ = new(Node)
+		t^.value = value
+		return
+	}
+
+	if value <= t^.value {
+		insert(&t^.left, value)
+	} else {
+		insert(&t^.right, value)
+	}
+}
+
+sorted_data :: proc(t: Tree) -> []int {
+
+	if t == nil { return nil }
+
+	acc: [dynamic]int
+	collect_data(t, &acc)
+	return acc[:]
+}
+
+collect_data :: proc(t: Tree, acc: ^[dynamic]int) {
+
+	if t == nil { return }
+	collect_data(t.left, acc)
+	append(acc, t.value)
+	collect_data(t.right, acc)
+}

exercises/practice/binary-search-tree/.meta/tests.toml

@@ -0,0 +1,40 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[e9c93a78-c536-4750-a336-94583d23fafa]
+description = "data is retained"
+
+[7a95c9e8-69f6-476a-b0c4-4170cb3f7c91]
+description = "insert data at proper node -> smaller number at left node"
+
+[22b89499-9805-4703-a159-1a6e434c1585]
+description = "insert data at proper node -> same number at left node"
+
+[2e85fdde-77b1-41ed-b6ac-26ce6b663e34]
+description = "insert data at proper node -> greater number at right node"
+
+[dd898658-40ab-41d0-965e-7f145bf66e0b]
+description = "can create complex tree"
+
+[9e0c06ef-aeca-4202-b8e4-97f1ed057d56]
+description = "can sort data -> can sort single number"
+
+[425e6d07-fceb-4681-a4f4-e46920e380bb]
+description = "can sort data -> can sort if second number is smaller than first"
+
+[bd7532cc-6988-4259-bac8-1d50140079ab]
+description = "can sort data -> can sort if second number is same as first"
+
+[b6d1b3a5-9d79-44fd-9013-c83ca92ddd36]
+description = "can sort data -> can sort if second number is greater than first"
+
+[d00ec9bd-1288-4171-b968-d44d0808c1c8]
+description = "can sort data -> can sort complex tree"

exercises/practice/binary-search-tree/binary_search_tree.odin

@@ -0,0 +1,22 @@
+package binary_search_tree
+
+Tree :: ^Node
+
+Node :: struct {
+	value: int,
+	left:  Tree,
+	right: Tree,
+}
+
+destroy_tree :: proc(t: Tree) {
+	// Implement this procedure.
+}
+
+insert :: proc(t: ^Tree, value: int) {
+	// Implement this procedure.
+}
+
+sorted_data :: proc(t: Tree) -> []int {
+	// Implement this procedure.
+	return nil
+}