From c54536d1a11a96036a2ec47d3c2634c500b07e0d Mon Sep 17 00:00:00 2001
From: krahets <krahets@163.com>
Date: Wed, 19 Jul 2023 16:37:12 +0800
Subject: [PATCH] Modify the problem of preorder_traversal_iii

---
 .../preorder_traversal_iii_compact.cpp                     | 3 ++-
 .../chapter_backtracking/preorder_traversal_iii_compact.cs | 1 +
 .../chapter_backtracking/preorder_traversal_iii_compact.go | 1 +
 .../preorder_traversal_iii_compact.java                    | 1 +
 .../chapter_backtracking/preorder_traversal_iii_compact.js | 1 +
 .../chapter_backtracking/preorder_traversal_iii_compact.py | 1 +
 .../chapter_backtracking/preorder_traversal_iii_compact.rs | 1 +
 .../preorder_traversal_iii_compact.swift                   | 1 +
 .../chapter_backtracking/preorder_traversal_iii_compact.ts | 1 +
 docs/chapter_backtracking/backtracking_algorithm.md        | 7 +++++--
 10 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/codes/cpp/chapter_backtracking/preorder_traversal_iii_compact.cpp b/codes/cpp/chapter_backtracking/preorder_traversal_iii_compact.cpp
index ee00f47f5..fa44b638e 100644
--- a/codes/cpp/chapter_backtracking/preorder_traversal_iii_compact.cpp
+++ b/codes/cpp/chapter_backtracking/preorder_traversal_iii_compact.cpp
@@ -10,7 +10,7 @@ vector<TreeNode *> path;
 vector<vector<TreeNode *>> res;
 
 /* 前序遍历：例题三 */
-static void preOrder(TreeNode *root) {
+void preOrder(TreeNode *root) {
     // 剪枝
     if (root == nullptr || root->val == 3) {
         return;
@@ -20,6 +20,7 @@ static void preOrder(TreeNode *root) {
     if (root->val == 7) {
         // 记录解
         res.push_back(path);
+        return;
     }
     preOrder(root->left);
     preOrder(root->right);
diff --git a/codes/csharp/chapter_backtracking/preorder_traversal_iii_compact.cs b/codes/csharp/chapter_backtracking/preorder_traversal_iii_compact.cs
index c17a6dd20..63175ac93 100644
--- a/codes/csharp/chapter_backtracking/preorder_traversal_iii_compact.cs
+++ b/codes/csharp/chapter_backtracking/preorder_traversal_iii_compact.cs
@@ -21,6 +21,7 @@ public class preorder_traversal_iii_compact {
         if (root.val == 7) {
             // 记录解
             res.Add(new List<TreeNode>(path));
+            return;
         }
         preOrder(root.left);
         preOrder(root.right);
diff --git a/codes/go/chapter_backtracking/preorder_traversal_iii_compact.go b/codes/go/chapter_backtracking/preorder_traversal_iii_compact.go
index fcf1b86b2..36ada5ca6 100644
--- a/codes/go/chapter_backtracking/preorder_traversal_iii_compact.go
+++ b/codes/go/chapter_backtracking/preorder_traversal_iii_compact.go
@@ -19,6 +19,7 @@ func preOrderIII(root *TreeNode, res *[][]*TreeNode, path *[]*TreeNode) {
 	if int(root.Val) == 7 {
 		// 记录解
 		*res = append(*res, *path)
+		return
 	}
 	preOrderIII(root.Left, res, path)
 	preOrderIII(root.Right, res, path)
diff --git a/codes/java/chapter_backtracking/preorder_traversal_iii_compact.java b/codes/java/chapter_backtracking/preorder_traversal_iii_compact.java
index 4ffbb6217..50c3c8c29 100644
--- a/codes/java/chapter_backtracking/preorder_traversal_iii_compact.java
+++ b/codes/java/chapter_backtracking/preorder_traversal_iii_compact.java
@@ -24,6 +24,7 @@ public class preorder_traversal_iii_compact {
         if (root.val == 7) {
             // 记录解
             res.add(new ArrayList<>(path));
+            return;
         }
         preOrder(root.left);
         preOrder(root.right);
diff --git a/codes/javascript/chapter_backtracking/preorder_traversal_iii_compact.js b/codes/javascript/chapter_backtracking/preorder_traversal_iii_compact.js
index d83b7b053..08c78b936 100644
--- a/codes/javascript/chapter_backtracking/preorder_traversal_iii_compact.js
+++ b/codes/javascript/chapter_backtracking/preorder_traversal_iii_compact.js
@@ -18,6 +18,7 @@ function preOrder(root, path, res) {
     if (root.val === 7) {
         // 记录解
         res.push([...path]);
+        return;
     }
     preOrder(root.left, path, res);
     preOrder(root.right, path, res);
diff --git a/codes/python/chapter_backtracking/preorder_traversal_iii_compact.py b/codes/python/chapter_backtracking/preorder_traversal_iii_compact.py
index 55bf24ee6..6ee7307bc 100644
--- a/codes/python/chapter_backtracking/preorder_traversal_iii_compact.py
+++ b/codes/python/chapter_backtracking/preorder_traversal_iii_compact.py
@@ -20,6 +20,7 @@ def pre_order(root: TreeNode) -> None:
     if root.val == 7:
         # 记录解
         res.append(list(path))
+        return
     pre_order(root.left)
     pre_order(root.right)
     # 回退
diff --git a/codes/rust/chapter_backtracking/preorder_traversal_iii_compact.rs b/codes/rust/chapter_backtracking/preorder_traversal_iii_compact.rs
index eaa046f2d..ebf895764 100644
--- a/codes/rust/chapter_backtracking/preorder_traversal_iii_compact.rs
+++ b/codes/rust/chapter_backtracking/preorder_traversal_iii_compact.rs
@@ -21,6 +21,7 @@ fn pre_order(res: &mut Vec<Vec<Rc<RefCell<TreeNode>>>>, path: &mut Vec<Rc<RefCel
         if node.borrow().val == 7 {
             // 记录解
             res.push(path.clone());
+            return;
         }
         pre_order(res, path, node.borrow().left.clone());
         pre_order(res, path, node.borrow().right.clone());
diff --git a/codes/swift/chapter_backtracking/preorder_traversal_iii_compact.swift b/codes/swift/chapter_backtracking/preorder_traversal_iii_compact.swift
index 581b89d2f..1d580ffa4 100644
--- a/codes/swift/chapter_backtracking/preorder_traversal_iii_compact.swift
+++ b/codes/swift/chapter_backtracking/preorder_traversal_iii_compact.swift
@@ -20,6 +20,7 @@ func preOrder(root: TreeNode?) {
     if root.val == 7 {
         // 记录解
         res.append(path)
+        return
     }
     preOrder(root: root.left)
     preOrder(root: root.right)
diff --git a/codes/typescript/chapter_backtracking/preorder_traversal_iii_compact.ts b/codes/typescript/chapter_backtracking/preorder_traversal_iii_compact.ts
index 571a2e5a0..245b5e4c4 100644
--- a/codes/typescript/chapter_backtracking/preorder_traversal_iii_compact.ts
+++ b/codes/typescript/chapter_backtracking/preorder_traversal_iii_compact.ts
@@ -23,6 +23,7 @@ function preOrder(
     if (root.val === 7) {
         // 记录解
         res.push([...path]);
+        return;
     }
     preOrder(root.left, path, res);
     preOrder(root.right, path, res);
diff --git a/docs/chapter_backtracking/backtracking_algorithm.md b/docs/chapter_backtracking/backtracking_algorithm.md
index 5e9c0ab4c..b3a64c7a7 100644
--- a/docs/chapter_backtracking/backtracking_algorithm.md
+++ b/docs/chapter_backtracking/backtracking_algorithm.md
@@ -199,9 +199,12 @@
 
 !!! question "例题三"
 
-    在二叉树中搜索所有值为 $7$ 的节点，返回根节点到这些节点的路径，**路径中不能包含值为 $3$ 的节点**。
+    在二叉树中搜索所有值为 $7$ 的节点，返回根节点到这些节点的路径，**路径中有且只有一个值为 $7$ 的节点，并且不能包含值为 $3$ 的节点**。
 
-**解题思路**：在例题二的基础上添加剪枝操作，当遇到值为 $3$ 的节点时，则终止继续搜索。
+**解题思路**：在例题二的基础上添加剪枝操作。
+
+- 当遇到值为 $7$ 的节点时，记录解并停止搜索。
+- 当遇到值为 $3$ 的节点时，则终止继续搜索。
 
 === "Java"