leetcood学习笔记-257-二叉树的所有路径

题目描述：

 第一次提交：参考113-路径总和②

class Solution:
    def binaryTreePaths(self, root: TreeNode) -> List[str]:
        r = []
        if not root:
            return r
        l = ""
        def path(root, l):
            if not root:
                return 
            l += str(root.val)
            if  not root.left and not root.right:
                r.append(l)
            l += "->"
            path(root.left,l)
            path(root.right,l)
            
        path(root,l)
        return r

方法二

class Solution:
    def binaryTreePaths(self, root):
        """
        :type root: TreeNode
        :rtype: List[str]
        """
        if root == None:
            return []
        if root.left == None and root.right == None:
            return [str(root.val)]
        paths = self.binaryTreePaths(root.left) + self.binaryTreePaths(root.right)
        for i in range(len(paths)):
            paths[i] = str(root.val) + '->' + paths[i]
        return paths