147 lines
4.1 KiB
JavaScript
147 lines
4.1 KiB
JavaScript
/**
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* File: binary_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 Tree = require("../include/TreeNode");
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const { printTree } = require("../include/PrintUtil");
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/* 二叉搜索树 */
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var root;
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function BinarySearchTree(nums) {
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nums.sort((a,b) => { return a-b }); // 排序数组
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root = buildTree(nums, 0, nums.length - 1); // 构建二叉搜索树
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}
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/* 获取二叉树根结点 */
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function getRoot() {
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return root;
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}
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/* 构建二叉搜索树 */
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function buildTree(nums, i, j) {
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if (i > j) return null;
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// 将数组中间结点作为根结点
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let mid = Math.floor((i + j) / 2);
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let root = new Tree.TreeNode(nums[mid]);
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// 递归建立左子树和右子树
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root.left = buildTree(nums, i, mid - 1);
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root.right = buildTree(nums, mid + 1, j);
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return root;
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}
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/* 查找结点 */
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function search(num) {
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let cur = root;
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// 循环查找，越过叶结点后跳出
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while (cur !== null) {
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// 目标结点在 root 的右子树中
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if (cur.val < num) cur = cur.right;
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// 目标结点在 root 的左子树中
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else if (cur.val > num) cur = cur.left;
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// 找到目标结点，跳出循环
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else break;
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}
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// 返回目标结点
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return cur;
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}
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/* 插入结点 */
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function insert(num) {
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// 若树为空，直接提前返回
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if (root === null) return null;
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let cur = root, pre = null;
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// 循环查找，越过叶结点后跳出
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while (cur !== null) {
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// 找到重复结点，直接返回
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if (cur.val === num) return null;
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pre = cur;
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// 插入位置在 root 的右子树中
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if (cur.val < num) cur = cur.right;
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// 插入位置在 root 的左子树中
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else cur = cur.left;
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}
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// 插入结点 val
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let node = new Tree.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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return node;
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}
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/* 删除结点 */
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function remove(num) {
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// 若树为空，直接提前返回
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if (root === null) return null;
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let cur = root, pre = null;
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// 循环查找，越过叶结点后跳出
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while (cur !== null) {
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// 找到待删除结点，跳出循环
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if (cur.val === num) break;
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pre = cur;
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// 待删除结点在 root 的右子树中
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if (cur.val < num) cur = cur.right;
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// 待删除结点在 root 的左子树中
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else cur = cur.left;
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}
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// 若无待删除结点，则直接返回
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if (cur === null) return null;
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// 子结点数量 = 0 or 1
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if (cur.left === null || cur.right === null) {
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// 当子结点数量 = 0 / 1 时， child = null / 该子结点
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let child = cur.left !== null ? cur.left : cur.right;
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// 删除结点 cur
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if (pre.left === cur) pre.left = child;
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else pre.right = child;
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}
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// 子结点数量 = 2
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else {
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// 获取中序遍历中 cur 的下一个结点
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let nex = min(cur.right);
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let tmp = nex.val;
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// 递归删除结点 nex
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remove(nex.val);
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// 将 nex 的值复制给 cur
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cur.val = tmp;
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}
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return cur;
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}
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/* 获取最小结点 */
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function min(root) {
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if (root === null) return root;
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// 循环访问左子结点，直到叶结点时为最小结点，跳出
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while (root.left !== null) {
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root = root.left;
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}
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return root;
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}
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/* Driver Code */
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/* 初始化二叉搜索树 */
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var nums = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 ];
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BinarySearchTree(nums)
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console.log("\n初始化的二叉树为\n");
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printTree(getRoot());
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/* 查找结点 */
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let node = search(5);
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console.log("\n查找到的结点对象为 " + node + "，结点值 = " + node.val);
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/* 插入结点 */
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node = insert(16);
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console.log("\n插入结点 16 后，二叉树为\n");
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printTree(getRoot());
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/* 删除结点 */
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remove(1);
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console.log("\n删除结点 1 后，二叉树为\n");
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printTree(getRoot());
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remove(2);
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console.log("\n删除结点 2 后，二叉树为\n");
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printTree(getRoot());
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remove(4);
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console.log("\n删除结点 4 后，二叉树为\n");
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printTree(getRoot());
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