Add breadth first traversal to BST

Signed-off-by: Darko Draskovic <[email protected]>

spec/binary-search-tree.spec.js

@@ -21,5 +21,5 @@ describe("Function", function () {
  difference.forEach((value) => expect(bst.lookup(value)).not.toBeNull());
 
  remove.forEach((value) => expect(bst.lookup(value)).toBeNull());
- })
-})
+ });
+});

spec/search.spec.js

@@ -0,0 +1,17 @@
+import {
+ BinarySearchTree
+} from '../src/data-structures/binary-search-tree.js'
+
+describe("Function", function () {
+ const values = [9, 4, 6, 20, 170, 15, 1];
+ const bfs = [9, 4, 20, 1, 6, 15, 170];
+ const dfs = [9, 4, 1, 6, 20, 15, 170];
+
+ it("breadth first traverses the binary search tree", function () {
+ const tree = new BinarySearchTree();
+ values.forEach(val => {
+ tree.insert(val);
+ });
+ expect(tree.bfs()).toEqual(bfs);
+ });
+});

src/algorithms/search.js

@@ -1,3 +1,7 @@
+import {
+ BinarySearchTree
+} from '../src/data-structures/binary-search-tree.js'
+
 // javascript built in search
 var beasts = ['Centaur', 'Godzilla',
  'Mosura', 'Minotaur', 'Hydra', 'Nessie'];
@@ -20,4 +24,18 @@ var beasts = ['Centaur', 'Godzilla',
 
  console.assert(beasts.includes('Nessie') == true);
  console.assert(beasts.includes('Cyclope') == false);
+
+ // BFS
+ const tree = new BinarySearchTree();
+ [9, 4, 6, 20, 170, 15, 1].forEach(val => {
+ tree.insert(val);
+ });
+ let bfs = tree.bfs();
+ // BFS result: [9, 4, 20, 1, 6, 15, 170]
+ // DFS result: [9, 4, 1, 6, 20, 15, 170]
+ console.log();
 })()
+
+function traverse(node) {
+
+}

src/data-structures/binary-search-tree.js

@@ -111,6 +111,22 @@ export class BinarySearchTree {
  }
  return null;
  }
+ bfs() {
+ let list = [];
+ let queue = [];
+ queue.push(this.root);
+
+ while (queue.length) {
+ let current = queue.shift();
+ list.push(current.value);
+ if (current.left) queue.push(current.left);
+ if (current.right) queue.push(current.right);
+ }
+ return list;
+ }
+ dfs() {
+
+ }
 }
 
 function traverse(node) {
@@ -122,33 +138,6 @@ function traverse(node) {
 
 (function test() {
  const bst = new BinarySearchTree();
- bst.insert(9);
- bst.insert(4);
- bst.insert(6);
- bst.insert(5);
- bst.insert(3);
- bst.insert(20);
- bst.insert(20);
- bst.insert(170);
- bst.insert(15);
- bst.insert(1);
- bst.insert(25);
- bst.insert(300);
- bst.insert(7);
- bst.insert(30);
-
- bst.remove(9); // root
- bst.remove(300); // leaf
- bst.remove(25); // leaf
- bst.remove(7); // single left child
- bst.remove(25); // single right child
- bst.remove(9); // root
- bst.remove(9); // remove non existing
- bst.remove(170);
- bst.remove(15); // root
-
  var tree = traverse(bst.root);
  console.dir(tree, { depth: null });
-
- console.log(bst.lookup(20));
 })()

src/data-structures/queue.js

@@ -27,19 +27,19 @@ class Queue {
  }
  dequeue() {
  if (!this.length) return null;
- 
+
  const first = this.first;
  this.first = this.first.next;
  this.length--;
 
  if (!this.length) this.last = null;
- 
+
  return first;
  }
  array() {
  const arr = [];
  let current = this.first;
- while(current) {
+ while (current) {
  arr.push(current.value);
  current = current.next;
  }
@@ -49,14 +49,14 @@ class Queue {
 
 class QueueStack {
  constructor() {
- this.stack = new Stack(); 
+ this.stack = new Stack();
  }
  enqueue(value) {
  this.stack.push(value);
  }
  dequeue() {
  if (this.stack.isEmpty()) return null;
- 
+
  const tmp = new Stack();
  while (this.stack.length > 1) {
  tmp.push(this.stack.pop().value);
@@ -89,35 +89,35 @@ export function test() {
  queue.enqueue(i);
  }
  console.log("len: " + queue.length);
- console.log("queue: "+ queue.array());
+ console.log("queue: " + queue.array());
 
  console.log("\ndequeue 1 item");
  queue.dequeue()
  console.log("len: " + queue.length);
- console.log("queue: "+ queue.array());
+ console.log("queue: " + queue.array());
 
  console.log("\ndequeue everything except last");
  while (queue.length > 1) {
  queue.dequeue();
  }
  console.log("len: " + queue.length);
- console.log("queue: "+ queue.array());
+ console.log("queue: " + queue.array());
 
  console.log("\ndequeue last");
  queue.dequeue()
  console.log("len: " + queue.length);
- console.log("queue: "+ queue.array());
+ console.log("queue: " + queue.array());
 
  console.log("\ndequeue empty queue");
  queue.dequeue()
  console.log("len: " + queue.length);
- console.log("queue: "+ queue.array());
+ console.log("queue: " + queue.array());
 
  console.log("\nenqueue " + n + " items");
  queue.enqueue(0);
  for (let i = 1; i < 10; i++) {
  queue.enqueue(i);
  }
  console.log("len: " + queue.length);
- console.log("queue: "+ queue.array());
+ console.log("queue: " + queue.array());
 }