From 82250d1fc947502b277fe04aebd059b62d05c607 Mon Sep 17 00:00:00 2001
From: Joshua <47053655+Joshua-Lu@users.noreply.github.com>
Date: Fri, 14 May 2021 00:54:12 +0800
Subject: [PATCH] =?UTF-8?q?Update=200257.=E4=BA=8C=E5=8F=89=E6=A0=91?=
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添加 0257.二叉树的所有路径 Java版本
---
 problems/0257.二叉树的所有路径.md | 40 +++++++++++++++++++++++
 1 file changed, 40 insertions(+)

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 a104b27c..c0746260 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
@@ -282,7 +282,47 @@ public:
 
 
 Java：
+```Java
+class Solution {
+    /**
+     * 递归法
+     */
+    public List<String> binaryTreePaths(TreeNode root) {
+        List<String> res = new ArrayList<>();
+        if (root == null) {
+            return res;
+        }
+        List<Integer> paths = new ArrayList<>();
+        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
+        if (root.left == null && root.right == null) {
+            // 输出
+            StringBuilder sb = new StringBuilder();
+            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());
+            return;
+        }
+        if (root.left != null) {
+            traversal(root.left, paths, res);
+            paths.remove(paths.size() - 1);// 回溯
+        }
+        if (root.right != null) {
+            traversal(root.right, paths, res);
+            paths.remove(paths.size() - 1);// 回溯
+        }
+    }
+}
+
+```
 
 Python：