140 lines
4.3 KiB
JavaScript
140 lines
4.3 KiB
JavaScript
/**
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* File: binary_search_tree.js
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* Created Time: 2022-12-04
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* Author: IsChristina (christinaxia77@foxmail.com)
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*/
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const { TreeNode } = require('../modules/TreeNode');
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const { printTree } = require('../modules/PrintUtil');
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/* Binary search tree */
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class BinarySearchTree {
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/* Constructor */
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constructor() {
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// Initialize empty tree
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this.root = null;
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}
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/* Get binary tree root node */
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getRoot() {
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return this.root;
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}
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/* Search node */
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search(num) {
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let cur = this.root;
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// Loop find, break after passing leaf nodes
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while (cur !== null) {
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// Target node is in cur's right subtree
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if (cur.val < num) cur = cur.right;
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// Target node is in cur's left subtree
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else if (cur.val > num) cur = cur.left;
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// Found target node, break loop
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else break;
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}
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// Return target node
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return cur;
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}
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/* Insert node */
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insert(num) {
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// If tree is empty, initialize root node
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if (this.root === null) {
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this.root = new TreeNode(num);
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return;
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}
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let cur = this.root,
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pre = null;
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// Loop find, break after passing leaf nodes
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while (cur !== null) {
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// Found duplicate node, thus return
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if (cur.val === num) return;
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pre = cur;
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// Insertion position is in cur's right subtree
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if (cur.val < num) cur = cur.right;
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// Insertion position is in cur's left subtree
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else cur = cur.left;
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}
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// Insert node
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const node = new TreeNode(num);
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if (pre.val < num) pre.right = node;
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else pre.left = node;
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}
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/* Remove node */
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remove(num) {
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// If tree is empty, return
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if (this.root === null) return;
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let cur = this.root,
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pre = null;
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// Loop find, break after passing leaf nodes
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while (cur !== null) {
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// Found node to be removed, break loop
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if (cur.val === num) break;
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pre = cur;
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// Node to be removed is in cur's right subtree
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if (cur.val < num) cur = cur.right;
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// Node to be removed is in cur's left subtree
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else cur = cur.left;
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}
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// If no node to be removed, return
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if (cur === null) return;
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// Number of child nodes = 0 or 1
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if (cur.left === null || cur.right === null) {
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// When the number of child nodes = 0/1, child = null/that child node
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const child = cur.left !== null ? cur.left : cur.right;
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// Remove node cur
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if (cur !== this.root) {
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if (pre.left === cur) pre.left = child;
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else pre.right = child;
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} else {
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// If the removed node is the root, reassign the root
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this.root = child;
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}
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}
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// Number of child nodes = 2
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else {
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// Get the next node in in-order traversal of cur
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let tmp = cur.right;
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while (tmp.left !== null) {
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tmp = tmp.left;
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}
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// Recursively remove node tmp
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this.remove(tmp.val);
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// Replace cur with tmp
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cur.val = tmp.val;
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}
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}
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}
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/* Driver Code */
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/* Initialize binary search tree */
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const bst = new BinarySearchTree();
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// Note that different insertion orders can result in various tree structures. This particular sequence creates a perfect binary tree
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const nums = [8, 4, 12, 2, 6, 10, 14, 1, 3, 5, 7, 9, 11, 13, 15];
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for (const num of nums) {
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bst.insert(num);
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}
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console.log('\nInitialized binary tree is\n');
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printTree(bst.getRoot());
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/* Search node */
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const node = bst.search(7);
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console.log('\nFound node object ' + node + ', node value = ' + node.val);
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/* Insert node */
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bst.insert(16);
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console.log('\nAfter inserting node 16, the binary tree is\n');
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printTree(bst.getRoot());
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/* Remove node */
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bst.remove(1);
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console.log('\nAfter removing node 1, the binary tree is\n');
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printTree(bst.getRoot());
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bst.remove(2);
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console.log('\nAfter removing node 2, the binary tree is\n');
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printTree(bst.getRoot());
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bst.remove(4);
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console.log('\nAfter removing node 4, the binary tree is\n');
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printTree(bst.getRoot());
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