From 1c911aadf009e9ee59773728c7a3082d898ef205 Mon Sep 17 00:00:00 2001
From: Oleksii Trekhleb <trehleb@gmail.com>
Date: Tue, 3 Apr 2018 07:50:30 +0300
Subject: [PATCH] Add binary search tree.

---
 src/data-structures/tree/BinaryTreeNode.js        |  5 ++++-
 .../tree/__test__/BinaryTreeNode.test.js          | 15 +++++++++++++++
 .../tree/binary-search-tree/BinarySearchTree.js   |  2 +-
 .../binary-search-tree/BinarySearchTreeNode.js    |  4 ++--
 4 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/data-structures/tree/BinaryTreeNode.js b/src/data-structures/tree/BinaryTreeNode.js
index c4edba28..74e77866 100644
--- a/src/data-structures/tree/BinaryTreeNode.js
+++ b/src/data-structures/tree/BinaryTreeNode.js
@@ -1,17 +1,20 @@
 export default class BinaryTreeNode {
-  constructor(value = null) {
+  constructor(value = null, parent = null) {
     this.left = null;
     this.right = null;
+    this.parent = parent;
     this.value = value;
   }
 
   setLeft(node) {
     this.left = node;
+    this.left.parent = this;
     return this;
   }
 
   setRight(node) {
     this.right = node;
+    this.right.parent = this;
     return this;
   }
 
diff --git a/src/data-structures/tree/__test__/BinaryTreeNode.test.js b/src/data-structures/tree/__test__/BinaryTreeNode.test.js
index 65ec5977..7f68015e 100644
--- a/src/data-structures/tree/__test__/BinaryTreeNode.test.js
+++ b/src/data-structures/tree/__test__/BinaryTreeNode.test.js
@@ -23,6 +23,21 @@ describe('BinaryTreeNode', () => {
     expect(rootNode.right.value).toBe(3);
   });
 
+  it('should set parent', () => {
+    const leftNode = new BinaryTreeNode(1);
+    const rightNode = new BinaryTreeNode(3);
+    const rootNode = new BinaryTreeNode(2);
+
+    rootNode
+      .setLeft(leftNode)
+      .setRight(rightNode);
+
+    expect(rootNode.parent).toBeNull();
+    expect(rootNode.left.parent.value).toBe(2);
+    expect(rootNode.right.parent.value).toBe(2);
+    expect(rootNode.right.parent).toEqual(rootNode);
+  });
+
   it('should traverse node', () => {
     const leftNode = new BinaryTreeNode(1);
     const rightNode = new BinaryTreeNode(3);
diff --git a/src/data-structures/tree/binary-search-tree/BinarySearchTree.js b/src/data-structures/tree/binary-search-tree/BinarySearchTree.js
index be440d70..904650ee 100644
--- a/src/data-structures/tree/binary-search-tree/BinarySearchTree.js
+++ b/src/data-structures/tree/binary-search-tree/BinarySearchTree.js
@@ -14,7 +14,7 @@ export default class BinarySearchTree {
   }
 
   remove(value) {
-    const nodeToRemove = this.findNode(value);
+    const nodeToRemove = this.root.find(value);
 
     if (!nodeToRemove) {
       throw new Error('Item not found in the tree');
diff --git a/src/data-structures/tree/binary-search-tree/BinarySearchTreeNode.js b/src/data-structures/tree/binary-search-tree/BinarySearchTreeNode.js
index 584ac182..144c250a 100644
--- a/src/data-structures/tree/binary-search-tree/BinarySearchTreeNode.js
+++ b/src/data-structures/tree/binary-search-tree/BinarySearchTreeNode.js
@@ -12,14 +12,14 @@ export default class BinarySearchTreeNode extends BinaryTreeNode {
       if (this.left) {
         this.left.insert(value);
       } else {
-        this.left = new BinarySearchTreeNode(value);
+        this.setLeft(new BinarySearchTreeNode(value));
       }
     } else if (value > this.value) {
       // Insert to the right.
       if (this.right) {
         this.right.insert(value);
       } else {
-        this.right = new BinarySearchTreeNode(value);
+        this.setRight(new BinarySearchTreeNode(value));
       }
     }