diff --git a/codes/java/chapter_tree/binary_search_tree.java b/codes/java/chapter_tree/binary_search_tree.java new file mode 100644 index 0000000..d338937 --- /dev/null +++ b/codes/java/chapter_tree/binary_search_tree.java @@ -0,0 +1,146 @@ +package chapter_tree; + +import java.util.*; +import include.*; + +class BinarySearchTree { + private TreeNode root; + + public BinarySearchTree(int[] nums) { + Arrays.sort(nums); // 排序数组 + root = buildTree(nums, 0, nums.length - 1); // 构建二叉搜索树 + } + + /* 获取二叉树根结点 */ + public TreeNode getRoot() { + return root; + } + + /* 构建二叉搜索树 */ + public TreeNode buildTree(int[] nums, int i, int j) { + if (i > j) return null; + // 将数组中间结点作为根结点 + int mid = (i + j) / 2; + TreeNode root = new TreeNode(nums[mid]); + // 递归建立左子树和右子树 + root.left = buildTree(nums, i, mid - 1); + root.right = buildTree(nums, mid + 1, j); + return root; + } + + /* 查找结点 */ + public TreeNode search(int num) { + TreeNode cur = root; + // 循环查找,越过叶结点后跳出 + while (cur != null) { + // 目标结点在 root 的右子树中 + if (cur.val < num) cur = cur.right; + // 目标结点在 root 的左子树中 + else if (cur.val > num) cur = cur.left; + // 找到目标结点,跳出循环 + else break; + } + // 返回目标结点 + return cur; + } + + /* 插入结点 */ + public TreeNode insert(int num) { + // 若树为空,直接提前返回 + if (root == null) return null; + TreeNode cur = root, pre = null; + // 循环查找,越过叶结点后跳出 + while (cur != null) { + // 找到重复结点,直接返回 + if (cur.val == num) return null; + pre = cur; + // 插入位置在 root 的右子树中 + if (cur.val < num) cur = cur.right; + // 插入位置在 root 的左子树中 + else cur = cur.left; + } + // 插入结点 val + TreeNode node = new TreeNode(num); + if (pre.val < num) pre.right = node; + else pre.left = node; + return node; + } + + /* 删除结点 */ + public TreeNode remove(int num) { + // 若树为空,直接提前返回 + if (root == null) return null; + TreeNode cur = root, pre = null; + // 循环查找,越过叶结点后跳出 + while (cur != null) { + // 找到待删除结点,跳出循环 + if (cur.val == num) break; + pre = cur; + // 待删除结点在 root 的右子树中 + if (cur.val < num) cur = cur.right; + // 待删除结点在 root 的左子树中 + else cur = cur.left; + } + // 若无待删除结点,则直接返回 + if (cur == null) return null; + // 子结点数量 = 0 or 1 + if (cur.left == null || cur.right == null) { + // 当子结点数量 = 0 / 1 时, child = null / 该子结点 + TreeNode child = cur.left != null ? cur.left : cur.right; + // 删除结点 cur + if (pre.left == cur) pre.left = child; + else pre.right = child; + } + // 子结点数量 = 2 + else { + // 获取中序遍历中 cur 的下一个结点 + TreeNode nex = min(cur.right); + int tmp = nex.val; + // 递归删除结点 nex + remove(nex.val); + // 将 nex 的值复制给 cur + cur.val = tmp; + } + return cur; + } + + /* 获取最小结点 */ + public TreeNode min(TreeNode root) { + if (root == null) return root; + // 循环访问左子结点,直到叶结点时为最小结点,跳出 + while (root.left != null) { + root = root.left; + } + return root; + } +} + +public class binary_search_tree { + public static void main(String[] args) { + /* 初始化二叉搜索树 */ + int[] nums = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 }; + BinarySearchTree bst = new BinarySearchTree(nums); + System.out.println("\n初始化的二叉树为\n"); + PrintUtil.printTree(bst.getRoot()); + + /* 查找结点 */ + TreeNode node = bst.search(5); + System.out.println("\n查找到的结点对象为 " + node + ",结点值 = " + node.val); + + /* 插入结点 */ + node = bst.insert(16); + System.out.println("\n插入结点 16 后,二叉树为\n"); + PrintUtil.printTree(bst.getRoot()); + + /* 删除结点 */ + bst.remove(1); + System.out.println("\n删除结点 1 后,二叉树为\n"); + PrintUtil.printTree(bst.getRoot()); + bst.remove(2); + System.out.println("\n删除结点 2 后,二叉树为\n"); + PrintUtil.printTree(bst.getRoot()); + bst.remove(4); + System.out.println("\n删除结点 4 后,二叉树为\n"); + PrintUtil.printTree(bst.getRoot()); + } +} diff --git a/docs/index.md b/docs/index.md index 9edc7fa..2b0b34a 100644 --- a/docs/index.md +++ b/docs/index.md @@ -23,3 +23,5 @@ TODO | 更新:列表 Java 代码、配图 | 2022-11-07 | | 新增:栈与队列 | 2022-11-09 | | 新增:树 | 2022-11-12 | +| 新增:二叉搜索树,
更新:二叉树、表格居中 | 2022-11-13 | +| 更新:二叉搜索树 | 2022-11-14 | diff --git a/docs/stylesheets/extra.css b/docs/stylesheets/extra.css index 19a1b72..9ba484d 100644 --- a/docs/stylesheets/extra.css +++ b/docs/stylesheets/extra.css @@ -19,4 +19,14 @@ --md-typeset-color: #FEFEFE; --md-typeset-a-color: #31BC5A; -} \ No newline at end of file +} + +/* Center Markdown Tables (requires md_in_html extension) */ +.center-table { + text-align: center; +} + +.md-typeset .center-table :is(td,th):not([align]) { + /* Reset alignment for table cells */ + text-align: initial; +} diff --git a/mkdocs.yml b/mkdocs.yml index 468f7a2..63c2ea0 100644 --- a/mkdocs.yml +++ b/mkdocs.yml @@ -17,7 +17,7 @@ theme: features: - announce.dismiss - content.code.annotate - # - content.tabs.link + - content.tabs.link - content.tooltips # - header.autohide # - navigation.expand