# \[257]\[简单]\[DFS] 二叉树的所有路径

## 解题思路

[257. 二叉树的所有路径](https://leetcode-cn.com/problems/binary-tree-paths/)

给定一个二叉树，返回所有从根节点到叶子节点的路径。

说明: 叶子节点是指没有子节点的节点。

示例:

```
输入:

   1
 /   \
2     3
 \
  5

输出: ["1->2->5", "1->3"]

解释: 所有根节点到叶子节点的路径为: 1->2->5, 1->3
```

## 解题思路

使用DFS探索整棵树.

```python
# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution:
    def binaryTreePaths(self, root: TreeNode) -> List[str]:
        res = []

        def dfs(node, path):
            if node is None:
                return

            path.append(str(node.val))
            if node.left is None and node.right is None:
                res.append('->'.join(path))
            else:
                dfs(node.left, path)
                dfs(node.right, path)
            path.pop()

        dfs(root, [])
        return res
```


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