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Commit 04e533e

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Bladefidztrekhleb
authored andcommitted
Add remove method (trekhleb#33)
Remove node in AvlTree with auto balancing. Fix issue: trekhleb#13 
1 parent ada4537 commit 04e533e

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2 files changed

+80
-0
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2 files changed

+80
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‎src/data-structures/tree/avl-tree/AvlTree.js‎

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@@ -16,6 +16,48 @@ export default class AvlTree extends BinarySearchTree {
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}
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}
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remove(value) {
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const nodeToRemove = this.root.find(value);
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if (!nodeToRemove) {
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throw new Error('Item not found in the tree');
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}
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// Recursively find target node, if found then delete and balance.
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// return nodeToRemove.value;
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this.root = this.removeRecv(this.root, nodeToRemove);
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}
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removeRecv(origin, node) {
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let newOrigin = origin;
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if (origin.value > node.value) {
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// Recursively traversing from left
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newOrigin.left = this.removeRecv(origin.left, node);
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} else if (origin.value < node.value) {
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// Recursively traversing from right
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newOrigin.right = this.removeRecv(origin.right, node);
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} else {
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if (origin.left == null) {
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// Forget right node
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return origin.right;
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}
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if (origin.right == null) {
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// Forget left node
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return origin.left;
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}
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// Recursively find min node from left subtree
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// more efficient traversing
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const parent = Object.assign({}, origin);
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newOrigin = parent.right.findMin();
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newOrigin.right = this.deleteMin(parent.right);
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newOrigin.left = parent.left;
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}
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// Balance and return root node
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return this.balance(newOrigin);
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}
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/**
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* @param {*} value
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* @return {boolean}
@@ -48,6 +90,8 @@ export default class AvlTree extends BinarySearchTree {
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this.rotateRightLeft(node);
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}
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}
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// Return the heap to avoid referenceError
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return node;
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}
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/**
@@ -156,4 +200,15 @@ export default class AvlTree extends BinarySearchTree {
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// Attach rootNode to the left of rightNode.
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rightNode.setLeft(rootNode);
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}
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deleteMin(node) {
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// Forget right node if has value
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if (node.left == null) return node.right;
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const newNode = node;
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newNode.left = this.deleteMin(node.left);
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// Balance and return root node
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return this.balance(newNode);
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}
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}

‎src/data-structures/tree/avl-tree/__test__/AvlTRee.test.js‎

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@@ -186,6 +186,31 @@ describe('AvlTree', () => {
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expect(tree.toString()).toBe('6,8,9,18,21,22,43');
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});
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it('should keep balance after removal', () => {
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const tree = new AvlTree();
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tree.insert(1);
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tree.insert(2);
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tree.insert(3);
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tree.insert(4);
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tree.insert(5);
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tree.insert(6);
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tree.insert(7);
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tree.insert(8);
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tree.insert(9);
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expect(tree.toString()).toBe('1,2,3,4,5,6,7,8,9');
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expect(tree.root.height).toBe(3);
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tree.remove(8);
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tree.remove(9);
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expect(tree.contains(8)).toBeFalsy();
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expect(tree.contains(9)).toBeFalsy();
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expect(tree.toString()).toBe('1,2,3,4,5,6,7');
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expect(tree.root.height).toBe(2);
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});
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it('should do left right rotation and keeping left right node safe', () => {
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const tree = new AvlTree();
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