feat(BinaryTreeNode): add BinaryTreeNode.from

Author: amejiarosario

package.json

@@ -14,7 +14,7 @@
   ],
   "scripts": {
     "test": "jest --verbose",
-    "watch": "jest --watch --verbose --coverage",
+    "watch": "jest --watch --coverage",
     "ci": "npx eslint src/ && jest --coverage",
     "coverage": "jest --coverage && open coverage/lcov-report/index.html",
     "coverage:win": "jest --coverage && cmd.exe /C start coverage/lcov-report/index.html",

src/data-structures/trees/binary-tree-node.js

@@ -172,6 +172,21 @@ class BinaryTreeNode {
     this.meta.data = value;
     return this;
   }
+
+  /**
+   * Convert Binary tree from an iterable (e.g. array)
+   * @param {array|string} iterable - The iterable
+   */
+  static from(iterable = []) {
+    const toBinaryTree = (array, index = 0) => {
+      if (index >= array.length) return null;
+      const node = new BinaryTreeNode(array[index]);
+      node.setLeftAndUpdateParent(toBinaryTree(array, index * 2 + 1));
+      node.setRightAndUpdateParent(toBinaryTree(array, index * 2 + 2));
+      return node;
+    };
+    return toBinaryTree(Array.from(iterable));
+  }
 }
 
 BinaryTreeNode.RIGHT = RIGHT;

src/data-structures/trees/binary-tree-node.spec.js

@@ -1,114 +1,167 @@
 const { BinaryTreeNode } = require('../../index');
 
+const { LEFT, RIGHT } = BinaryTreeNode;
+
 describe('Binary Tree Node', () => {
   let treeNode;
 
-  beforeEach(() => {
-    treeNode = new BinaryTreeNode('hola');
-  });
-
-  it('should start with null parent', () => {
-    expect(treeNode.parent).toBe(null);
-  });
-
-  it('should start with empty metadata', () => {
-    expect(treeNode.meta).toEqual({});
-  });
-
-  it('should hold a value', () => {
-    expect(treeNode.value).toBe('hola');
-  });
-
-  it('should have a height 0', () => {
-    expect(treeNode.height).toBe(0);
-  });
-
-  it('should set/get left node', () => {
-    expect(treeNode.left).toBe(null);
-    const newNode = new BinaryTreeNode(1);
-    treeNode.setLeftAndUpdateParent(newNode);
-    expect(treeNode.left.value).toBe(1);
-
-    expect(newNode.parent).toBe(treeNode);
-    expect(treeNode.height).toBe(1);
-    expect(treeNode.balanceFactor).toBe(1);
-  });
-
-  it('should set/get right node', () => {
-    expect(treeNode.right).toBe(null);
-    const newNode = new BinaryTreeNode(1);
-    treeNode.setRightAndUpdateParent(newNode);
-
-    expect(treeNode.right.value).toBe(1);
-    expect(newNode.parent).toBe(treeNode);
-    expect(treeNode.height).toBe(1);
-    expect(treeNode.balanceFactor).toBe(-1);
-  });
-
-  describe('Family operations', () => {
-    let g;
-    let p;
-    let u;
-    let c;
-    let s;
-
+  describe('with instance', () => {
     beforeEach(() => {
-      g = new BinaryTreeNode('grandparent');
-      p = new BinaryTreeNode('parent');
-      u = new BinaryTreeNode('uncle');
-      c = new BinaryTreeNode('child');
-      s = new BinaryTreeNode('sibling');
-
-      g.setRightAndUpdateParent(p);
-      g.setLeftAndUpdateParent(u);
-      p.setRightAndUpdateParent(c);
-      p.setLeftAndUpdateParent(s);
+      treeNode = new BinaryTreeNode('hola');
     });
 
-    it('should set heights', () => {
-      expect(g.height).toBe(2);
-      expect(g.balanceFactor).toBe(-1);
-
-      expect(p.height).toBe(1);
-      expect(p.balanceFactor).toBe(0);
+    it('should start with null parent', () => {
+      expect(treeNode.parent).toBe(null);
+    });
 
-      expect(u.height).toBe(0);
-      expect(u.balanceFactor).toBe(0);
+    it('should start with empty metadata', () => {
+      expect(treeNode.meta).toEqual({});
     });
 
-    it('should get the sibling', () => {
-      expect(c.sibling).toBe(s);
-      expect(p.sibling).toBe(u);
+    it('should hold a value', () => {
+      expect(treeNode.value).toBe('hola');
     });
 
-    it('should set leaf correctly', () => {
-      expect(c.isLeaf).toBe(true);
-      expect(u.isLeaf).toBe(true);
-      expect(p.isLeaf).toBe(false);
-      expect(g.isLeaf).toBe(false);
+    it('should have a height 0', () => {
+      expect(treeNode.height).toBe(0);
     });
 
-    it('should get null if no sibling', () => {
-      expect(g.sibling).toBe(null);
+    it('should set/get left node', () => {
+      expect(treeNode.left).toBe(null);
+      const newNode = new BinaryTreeNode(1);
+      treeNode.setLeftAndUpdateParent(newNode);
+      expect(treeNode.left.value).toBe(1);
+
+      expect(newNode.parent).toBe(treeNode);
+      expect(treeNode.height).toBe(1);
+      expect(treeNode.balanceFactor).toBe(1);
     });
 
-    it('should get the uncle', () => {
-      expect(c.uncle).toBe(u);
+    it('should set/get right node', () => {
+      expect(treeNode.right).toBe(null);
+      const newNode = new BinaryTreeNode(1);
+      treeNode.setRightAndUpdateParent(newNode);
+
+      expect(treeNode.right.value).toBe(1);
+      expect(newNode.parent).toBe(treeNode);
+      expect(treeNode.height).toBe(1);
+      expect(treeNode.balanceFactor).toBe(-1);
     });
 
-    it('should get null if no uncle', () => {
-      expect(g.uncle).toBe(null);
-      expect(p.uncle).toBe(null);
+    describe('Family operations', () => {
+      let g;
+      let p;
+      let u;
+      let c;
+      let s;
+
+      beforeEach(() => {
+        g = new BinaryTreeNode('grandparent');
+        p = new BinaryTreeNode('parent');
+        u = new BinaryTreeNode('uncle');
+        c = new BinaryTreeNode('child');
+        s = new BinaryTreeNode('sibling');
+
+        g.setRightAndUpdateParent(p);
+        g.setLeftAndUpdateParent(u);
+        p.setRightAndUpdateParent(c);
+        p.setLeftAndUpdateParent(s);
+      });
+
+      it('should set heights', () => {
+        expect(g.height).toBe(2);
+        expect(g.balanceFactor).toBe(-1);
+
+        expect(p.height).toBe(1);
+        expect(p.balanceFactor).toBe(0);
+
+        expect(u.height).toBe(0);
+        expect(u.balanceFactor).toBe(0);
+      });
+
+      it('should get the sibling', () => {
+        expect(c.sibling).toBe(s);
+        expect(p.sibling).toBe(u);
+      });
+
+      it('should set leaf correctly', () => {
+        expect(c.isLeaf).toBe(true);
+        expect(u.isLeaf).toBe(true);
+        expect(p.isLeaf).toBe(false);
+        expect(g.isLeaf).toBe(false);
+      });
+
+      it('should get null if no sibling', () => {
+        expect(g.sibling).toBe(null);
+      });
+
+      it('should get the uncle', () => {
+        expect(c.uncle).toBe(u);
+      });
+
+      it('should get null if no uncle', () => {
+        expect(g.uncle).toBe(null);
+        expect(p.uncle).toBe(null);
+      });
+
+      it('true if is parent left child', () => {
+        expect(s.isParentLeftChild).toBe(true);
+        expect(s.isParentRightChild).toBe(false);
+      });
+
+      it('true if is parent left child', () => {
+        expect(c.isParentLeftChild).toBe(false);
+        expect(c.isParentRightChild).toBe(true);
+      });
     });
+  });
 
-    it('true if is parent left child', () => {
-      expect(s.isParentLeftChild).toBe(true);
-      expect(s.isParentRightChild).toBe(false);
+  describe('with static methods', () => {
+    it('should work with null', () => {
+      const tree = BinaryTreeNode.from();
+      expect(tree).toEqual(null);
     });
 
-    it('true if is parent left child', () => {
-      expect(c.isParentLeftChild).toBe(false);
-      expect(c.isParentRightChild).toBe(true);
+    it('should build from array', () => {
+      /*
+                        0
+                       / \
+                      1   2
+                     / \   \
+                    3   5   4
+      */
+      const tree = BinaryTreeNode.from([0, 1, 2, 3, 5, null, 4]);
+      expect(tree.toValues()).toEqual({
+        value: 0,
+        left: 1,
+        right: 2,
+        parent: null,
+        parentSide: null,
+      });
+
+      expect(tree.left.toValues()).toEqual({
+        value: 1,
+        left: 3,
+        right: 5,
+        parent: 0,
+        parentSide: LEFT,
+      });
+
+      expect(tree.right.toValues()).toEqual({
+        value: 2,
+        left: null,
+        right: 4,
+        parent: 0,
+        parentSide: RIGHT,
+      });
+
+      expect(tree.right.right.toValues()).toEqual({
+        value: 4,
+        left: null,
+        right: null,
+        parent: 2,
+        parentSide: RIGHT,
+      });
     });
   });
 });