121 lines
4.4 KiB
Markdown
121 lines
4.4 KiB
Markdown
---
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id: 587d8258367417b2b2512c81
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title: Delete a Node with One Child in a Binary Search Tree
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challengeType: 1
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videoUrl: ''
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localeTitle: ''
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---
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## Description
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undefined
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## Instructions
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undefined
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: ''
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() }; return (typeof test == "object")})(), "The <code>BinarySearchTree</code> data structure exists.");'
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- text: ''
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; return (typeof test.remove == "function")})(), "The binary search tree has a method called <code>remove</code>.");'
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- text: ''
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; if (typeof test.remove !== "function") { return false; }; return (test.remove(100) == null); })(), "Trying to remove an element that does not exist returns <code>null</code>.");'
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- text: ''
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; if (typeof test.remove !== "function") { return false; }; test.add(500); test.remove(500); return (test.inorder() == null); })(), "If the root node has no children, deleting it sets the root to <code>null</code>.");'
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- text: ''
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; if (typeof test.remove !== "function") { return false; }; test.add(5); test.add(3); test.add(7); test.add(6); test.add(10); test.add(12); test.remove(3); test.remove(12); test.remove(10); return (test.inorder().join("") == "567"); })(), "The <code>remove</code> method removes leaf nodes from the tree");'
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- text: ''
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; if (typeof test.remove !== "function") { return false; }; test.add(-1); test.add(3); test.add(7); test.add(16); test.remove(16); test.remove(7); test.remove(3); return (test.inorder().join("") == "-1"); })(), "The <code>remove</code> method removes nodes with one child.");'
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- text: ''
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testString: 'assert((function() { var test = false; if (typeof BinarySearchTree !== "undefined") { test = new BinarySearchTree() } else { return false; }; if (typeof test.remove !== "function") { return false; }; test.add(15); test.add(27); test.remove(15); return (test.inorder().join("") == "27"); })(), "Removing the root in a tree with two nodes sets the second to be the root.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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var displayTree = (tree) => console.log(JSON.stringify(tree, null, 2));
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function Node(value) {
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this.value = value;
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this.left = null;
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this.right = null;
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}
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function BinarySearchTree() {
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this.root = null;
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this.remove = function(value) {
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if (this.root === null) {
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return null;
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}
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var target;
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var parent = null;
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// find the target value and its parent
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(function findValue(node = this.root) {
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if (value == node.value) {
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target = node;
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} else if (value < node.value && node.left !== null) {
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parent = node;
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return findValue(node.left);
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} else if (value < node.value && node.left === null) {
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return null;
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} else if (value > node.value && node.right !== null) {
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parent = node;
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return findValue(node.right);
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} else {
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return null;
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}
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}).bind(this)();
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if (target === null) {
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return null;
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}
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// count the children of the target to delete
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var children = (target.left !== null ? 1 : 0) + (target.right !== null ? 1 : 0);
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// case 1: target has no children
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if (children === 0) {
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if (target == this.root) {
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this.root = null;
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}
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else {
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if (parent.left == target) {
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parent.left = null;
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} else {
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parent.right = null;
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}
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}
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}
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// case 2: target has one child, change code below this line
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};
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}
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```
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</div>
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### After Test
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<div id='js-teardown'>
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```js
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console.info('after the test');
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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