Add a chapter of binary tree.

codes/java/chapter_computational_complexity/leetcode_two_sum.java

@@ -1,4 +1,4 @@
-package chapter_computational_complexity.space_time_tradeoff;
+package chapter_computational_complexity;
 
 import java.util.*;
 
@@ -36,10 +36,11 @@ public class leetcode_two_sum {
         int target = 9;
         
         // ====== Driver Code ======
+        // 方法一
         solution_brute_force slt1 = new solution_brute_force();
         int[] res = slt1.twoSum(nums, target);
         System.out.println(Arrays.toString(res));
-
+        // 方法二
         solution_hash_map slt2 = new solution_hash_map();
         res = slt2.twoSum(nums, target);
         System.out.println(Arrays.toString(res));

codes/java/chapter_computational_complexity/space_complexity_types.java

@@ -1,4 +1,4 @@
-package chapter_computational_complexity.space_complexity;
+package chapter_computational_complexity;
 
 import include.*;
 import java.util.*;

codes/java/chapter_computational_complexity/time_complexity_types.java

@@ -1,4 +1,4 @@
-package chapter_computational_complexity.time_complexity;
+package chapter_computational_complexity;
 
 public class time_complexity_types {
     /* 常数阶 */

codes/java/chapter_computational_complexity/worst_best_time_complexity.java

@@ -1,4 +1,4 @@
-package chapter_computational_complexity.time_complexity;
+package chapter_computational_complexity;
 
 import java.util.*;
 

codes/java/chapter_stack_and_queue/array_queue.java

@@ -45,7 +45,7 @@ class ArrayQueue {
 
     /* 出队 */
     public int poll() {
-        // 删除头节点
+        // 删除头结点
         if (isEmpty())
             throw new EmptyStackException();
         int num = nums[front];
@@ -56,7 +56,7 @@ class ArrayQueue {
 
     /* 访问队首元素 */
     public int peek() {
-        // 删除头节点
+        // 删除头结点
         if (isEmpty())
             throw new EmptyStackException();
         return nums[front];

codes/java/chapter_stack_and_queue/linkedlist_queue.java

@@ -29,7 +29,7 @@ class LinkedListQueue {
 
     /* 出队 */
     public int poll() {
-        // 删除头节点
+        // 删除头结点
         return list.removeFirst();
     }
 

codes/java/chapter_tree/binary_tree.java

@@ -0,0 +1,34 @@
+package chapter_tree;
+
+import include.*;
+
+public class binary_tree {
+    public static void main(String[] args) {
+        /* 初始化二叉树 */
+        // 初始化结点
+        TreeNode n1 = new TreeNode(1);
+        TreeNode n2 = new TreeNode(2);
+        TreeNode n3 = new TreeNode(3);
+        TreeNode n4 = new TreeNode(4);
+        TreeNode n5 = new TreeNode(5);
+        // 构建引用指向（即指针）
+        n1.left = n2;
+        n1.right = n3;
+        n2.left = n4;
+        n2.right = n5;
+        System.out.println("\n初始化二叉树\n");
+        PrintUtil.printTree(n1);
+
+        /* 插入与删除结点 */
+        TreeNode P = new TreeNode(0);
+        // 在 n1 -> n2 中间插入结点 P
+        n1.left = P;
+        P.left = n2;
+        System.out.println("\n插入结点 P 后\n");
+        PrintUtil.printTree(n1);
+        // 删除结点 P
+        n1.left = n2;
+        System.out.println("\n删除结点 P 后\n");
+        PrintUtil.printTree(n1);
+    }
+}

codes/java/chapter_tree/binary_tree_bfs.java

@@ -0,0 +1,36 @@
+package chapter_tree;
+
+import include.*;
+import java.util.*;
+
+public class binary_tree_bfs {
+    /* 层序遍历 */
+    static List<Integer> hierOrder(TreeNode root) {
+        // 初始化队列，加入根结点
+        Queue<TreeNode> queue = new LinkedList<>() {{ add(root); }};
+        // 初始化一个列表，用于保存遍历序列
+        List<Integer> list = new ArrayList<>();
+        while (!queue.isEmpty()) {
+            TreeNode node = queue.poll();  // 队列出队
+            list.add(node.val);            // 保存结点
+            if (node.left != null)
+                queue.offer(node.left);    // 左子结点入队
+            if (node.right != null)
+                queue.offer(node.right);   // 右子结点入队
+        }
+        return list;
+    }
+
+    public static void main(String[] args) {
+        /* 初始化二叉树 */
+        // 这里借助了一个从数组直接生成二叉树的函数
+        TreeNode root = TreeNode.arrToTree(new Integer[] {
+                1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null });
+        System.out.println("\n初始化二叉树\n");
+        PrintUtil.printTree(root);
+
+        /* 层序遍历 */
+        List<Integer> list = hierOrder(root);
+        System.out.println("\n层序遍历的结点打印序列 = " + list);
+    }
+}

codes/java/chapter_tree/binary_tree_dfs.java

@@ -0,0 +1,60 @@
+package chapter_tree;
+
+import include.*;
+import java.util.*;
+
+public class binary_tree_dfs {
+    // 初始化列表，用于存储遍历序列
+    static ArrayList<Integer> list = new ArrayList<>();
+
+    /* 前序遍历 */
+    static void preOrder(TreeNode root) {
+        if (root == null) return;
+        // 访问优先级：根结点 -> 左子树 -> 右子树
+        list.add(root.val);
+        preOrder(root.left);
+        preOrder(root.right);
+    }
+
+    /* 中序遍历 */
+    static void inOrder(TreeNode root) {
+        if (root == null) return;
+        // 访问优先级：左子树 -> 根结点 -> 右子树
+        inOrder(root.left);
+        list.add(root.val);
+        inOrder(root.right);
+    }
+
+    /* 后序遍历 */
+    static void postOrder(TreeNode root) {
+        if (root == null) return;
+        // 访问优先级：左子树 -> 右子树 -> 根结点
+        postOrder(root.left);
+        postOrder(root.right);
+        list.add(root.val);
+    }
+
+    public static void main(String[] args) {
+        /* 初始化二叉树 */
+        // 这里借助了一个从数组直接生成二叉树的函数
+        TreeNode root = TreeNode.arrToTree(new Integer[] { 
+            1, 2, 3, 4, 5, 6, 7, null, null, null, null, null, null, null, null});
+        System.out.println("\n初始化二叉树\n");
+        PrintUtil.printTree(root);
+
+        /* 前序遍历 */
+        list.clear();
+        preOrder(root);
+        System.out.println("\n前序遍历的结点打印序列 = " + list);
+
+        /* 中序遍历 */
+        list.clear();
+        inOrder(root);
+        System.out.println("\n中序遍历的结点打印序列 = " + list);
+
+        /* 后序遍历 */
+        list.clear();
+        postOrder(root);
+        System.out.println("\n后序遍历的结点打印序列 = " + list);
+    }
+}

docs/index.md

@@ -22,3 +22,4 @@ TODO
 | 更新：各章节 Java 代码 | 2022-11-06 |
 | 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 |

mkdocs.yml

@@ -20,11 +20,11 @@ theme:
     # - content.tabs.link
     - content.tooltips
     # - header.autohide
-    - navigation.expand
+    # - navigation.expand
     - navigation.indexes
     # - navigation.instant
     # - navigation.prune
-    - navigation.sections
+    # - navigation.sections
     # - navigation.tabs
     # - navigation.tabs.sticky
     # - navigation.top
@@ -139,6 +139,14 @@ nav:
     - chapter_stack_and_queue/index.md
     - 栈: chapter_stack_and_queue/stack.md
     - 队列: chapter_stack_and_queue/queue.md
+    - 双向队列: chapter_stack_and_queue/deque.md
     - 小结: chapter_stack_and_queue/summary.md
+  - 树:
+    - chapter_tree/index.md
+    - 二叉树: chapter_tree/binary_tree.md
+    - 满二叉树: chapter_tree/perfect_complete_full_binary_tree.md
+    - 二叉搜索树: chapter_tree/binary_search_tree.md
+    - 平衡二叉树: chapter_tree/balanced_binary_tree.md
+    - 小结: chapter_tree/summary.md
   - License:
     - chapter_license/index.md