Merge pull request #113 from justin-tse/master

Add the TypeScript code and docs for Chapter of Tree

docs/chapter_tree/binary_search_tree.md

@@ -132,7 +132,22 @@ comments: true
 === "TypeScript"
 
     ```typescript title="binary_search_tree.ts"
-
+    /* 查找结点 */
+    function search(num: number): TreeNode | null {
+        let cur = root;
+        // 循环查找，越过叶结点后跳出
+        while (cur !== null) {
+            if (cur.val < num) {
+                cur = cur.right; // 目标结点在 root 的右子树中
+            } else if (cur.val > num) {
+                cur = cur.left; // 目标结点在 root 的左子树中
+            } else {
+                break; // 找到目标结点，跳出循环
+            }
+        }
+        // 返回目标结点
+        return cur;
+    }
     ```
 
 === "C"
@@ -280,7 +295,35 @@ comments: true
 === "TypeScript"
 
     ```typescript title="binary_search_tree.ts"
-
+    /* 插入结点 */
+    function insert(num: number): TreeNode | null {
+        // 若树为空，直接提前返回
+        if (root === null) {
+            return null;
+        }
+        let cur = root,
+            pre: TreeNode | null = null;
+        // 循环查找，越过叶结点后跳出
+        while (cur !== null) {
+            if (cur.val === num) {
+                return null; // 找到重复结点，直接返回
+            }
+            pre = cur;
+            if (cur.val < num) {
+                cur = cur.right as TreeNode; // 插入位置在 root 的右子树中
+            } else {
+                cur = cur.left as TreeNode; // 插入位置在 root 的左子树中
+            }
+        }
+        // 插入结点 val
+        let node = new TreeNode(num);
+        if (pre!.val < num) {
+            pre!.right = node;
+        } else {
+            pre!.left = node;
+        }
+        return node;
+    }
     ```
 
 === "C"
@@ -547,7 +590,54 @@ comments: true
 === "TypeScript"
 
     ```typescript title="binary_search_tree.ts"
-
+    /* 删除结点 */
+    function remove(num: number): TreeNode | null {
+        // 若树为空，直接提前返回
+        if (root === null) {
+            return null;
+        }
+        let cur = root,
+            pre: TreeNode | null = 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;
+            if (cur.val < num) {
+                cur = cur.right as TreeNode; // 待删除结点在 root 的右子树中
+            } else {
+                cur = cur.left as TreeNode; // 待删除结点在 root 的左子树中
+            }
+        }
+        // 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
+            let 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
+            let next = min(cur.right);
+            let tmp = next!.val;
+            // 递归删除结点 nex
+            remove(next!.val);
+            // 将 nex 的值复制给 cur
+            cur.val = tmp;
+        }
+        return cur;
+    }
     ```
 
 === "C"

docs/chapter_tree/binary_tree.md

@@ -74,7 +74,18 @@ comments: true
 === "TypeScript"
 
     ```typescript title=""
+    /* 链表结点类 */
+    class TreeNode {
+        val: number;
+        left: TreeNode | null;
+        right: TreeNode | null;
 
+        constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+            this.val = val === undefined ? 0 : val; // 结点值
+            this.left = left === undefined ? null : left; // 左子结点指针
+            this.right = right === undefined ? null : right; // 右子结点指针
+        }
+    }
     ```
 
 === "C"
@@ -215,7 +226,18 @@ comments: true
 === "TypeScript"
 
     ```typescript title="binary_tree.ts"
-
+    /* 初始化二叉树 */
+    // 初始化结点
+    let n1 = new TreeNode(1),
+        n2 = new TreeNode(2),
+        n3 = new TreeNode(3),
+        n4 = new TreeNode(4),
+        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;
     ```
 
 === "C"
@@ -273,7 +295,6 @@ comments: true
     p := NewTreeNode(0)
     n1.Left = p
     p.Left = n2
-
     // 删除结点 P
     n1.Left = n2
     ```
@@ -286,7 +307,6 @@ comments: true
     // 在 n1 -> n2 中间插入结点 P
     n1.left = P;
     P.left = n2;
-
     // 删除结点 P
     n1.left = n2;
     ```
@@ -294,7 +314,13 @@ comments: true
 === "TypeScript"
 
     ```typescript title="binary_tree.ts"
-
+    /* 插入与删除结点 */
+    const P = new TreeNode(0);
+    // 在 n1 -> n2 中间插入结点 P
+    n1.left = P;
+    P.left = n2;
+    // 删除结点 P
+    n1.left = n2;
     ```
 
 === "C"
@@ -423,7 +449,6 @@ comments: true
                 queue.push(node.left);    // 左子结点入队
             if (node.right)
                 queue.push(node.right);   // 右子结点入队
-            
         }
         return list;
     }
@@ -432,7 +457,24 @@ comments: true
 === "TypeScript"
 
     ```typescript title="binary_tree_bfs.ts"
-
+    /* 层序遍历 */
+    function hierOrder(root: TreeNode | null): number[] {
+        // 初始化队列，加入根结点
+        const queue = [root];
+        // 初始化一个列表，用于保存遍历序列
+        const list: number[] = [];
+        while (queue.length) {
+            let node = queue.shift() as TreeNode; // 队列出队
+            list.push(node.val); // 保存结点
+            if (node.left) {
+                queue.push(node.left); // 左子结点入队
+            }
+            if (node.right) {
+                queue.push(node.right); // 右子结点入队
+            }
+        }
+        return list;
+    }
     ```
 
 === "C"
@@ -606,7 +648,38 @@ comments: true
 === "TypeScript"
 
     ```typescript title="binary_tree_dfs.ts"
+    /* 前序遍历 */
+    function preOrder(root: TreeNode | null): void {
+        if (root === null) {
+            return;
+        }
+        // 访问优先级：根结点 -> 左子树 -> 右子树
+        list.push(root.val);
+        preOrder(root.left);
+        preOrder(root.right);
+    }
 
+    /* 中序遍历 */
+    function inOrder(root: TreeNode | null): void {
+        if (root === null) {
+            return;
+        }
+        // 访问优先级：左子树 -> 根结点 -> 右子树
+        inOrder(root.left);
+        list.push(root.val);
+        inOrder(root.right);
+    }
+
+    /* 后序遍历 */
+    function postOrder(root: TreeNode | null): void {
+        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.push(root.val);
+    }
     ```
 
 === "C"