From 026f8ca7b4c189dac475ea2b8f93923c8abfed89 Mon Sep 17 00:00:00 2001
From: hbingzhi <houbingzhi123@gmail.com>
Date: Sat, 21 Jan 2023 17:25:14 +0800
Subject: [PATCH] =?UTF-8?q?257.=E7=BB=99Java=E8=A7=A3=E6=B3=95=E6=B7=BB?=
 =?UTF-8?q?=E5=8A=A0=E6=9B=B4=E5=85=A8=E9=9D=A2=E6=B8=85=E6=99=B0=E7=9A=84?=
 =?UTF-8?q?=E6=B3=A8=E9=87=8A=EF=BC=8C=E5=8F=A6=E4=BF=AE=E6=94=B9=E4=B8=80?=
 =?UTF-8?q?=E5=A4=84=E9=87=8D=E5=A4=8D=E7=9A=84=E7=AC=94=E8=AF=AF?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0257.二叉树的所有路径.md | 26 ++++++++++++-----------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/problems/0257.二叉树的所有路径.md b/problems/0257.二叉树的所有路径.md
index d0c190a0..68434479 100644
--- a/problems/0257.二叉树的所有路径.md
+++ b/problems/0257.二叉树的所有路径.md
@@ -34,7 +34,7 @@
 
 ## 递归
 
-1. 递归函数函数参数以及返回值
+1. 递归函数参数以及返回值
 
 要传入根节点，记录每一条路径的path，和存放结果集的result，这里递归不需要返回值，代码如下：
 
@@ -259,7 +259,7 @@ if (cur->right) {
     path.pop_back(); // 回溯 '>' 
     path.pop_back(); //  回溯 '-' 
 }
-``` 
+```
 
 整体代码如下： 
 
@@ -395,33 +395,34 @@ class Solution {
      * 递归法
      */
     public List<String> binaryTreePaths(TreeNode root) {
-        List<String> res = new ArrayList<>();
+        List<String> res = new ArrayList<>();// 存最终的结果
         if (root == null) {
             return res;
         }
-        List<Integer> paths = new ArrayList<>();
+        List<Integer> paths = new ArrayList<>();// 作为结果中的路径
         traversal(root, paths, res);
         return res;
     }
 
     private void traversal(TreeNode root, List<Integer> paths, List<String> res) {
-        paths.add(root.val);
-        // 叶子结点
+        paths.add(root.val);// 前序遍历，中
+        // 遇到叶子结点
         if (root.left == null && root.right == null) {
             // 输出
-            StringBuilder sb = new StringBuilder();
+            StringBuilder sb = new StringBuilder();// StringBuilder用来拼接字符串，速度更快
             for (int i = 0; i < paths.size() - 1; i++) {
                 sb.append(paths.get(i)).append("->");
             }
-            sb.append(paths.get(paths.size() - 1));
-            res.add(sb.toString());
+            sb.append(paths.get(paths.size() - 1));// 记录最后一个节点
+            res.add(sb.toString());// 收集一个路径
             return;
         }
-        if (root.left != null) {
+        // 递归和回溯是同时进行，所以要放在同一个花括号里
+        if (root.left != null) { // 左
             traversal(root.left, paths, res);
             paths.remove(paths.size() - 1);// 回溯
         }
-        if (root.right != null) {
+        if (root.right != null) { // 右
             traversal(root.right, paths, res);
             paths.remove(paths.size() - 1);// 回溯
         }
@@ -794,7 +795,7 @@ object Solution {
   }
 }
 ```
-	
+
 rust:
 
 ```rust
@@ -826,3 +827,4 @@ impl Solution {
 <a href="https://programmercarl.com/other/kstar.html" target="_blank">
   <img src="../pics/网站星球宣传海报.jpg" width="1000"/>
 </a>
+