Binary-Tree-Paths

第89天。

Given a binary tree, return all root-to-leaf paths.

For example, given the following binary tree:

1 /
2 3
5

All root-to-leaf paths are:

[“1->2->5”, “1->3”]

比较的简单的题目，直接用递归做就好了，因为python写起来比较简单，所以这里用python实现：

def binaryTreePaths(self, root):
    """
    :type root: TreeNode
    :rtype: List[str]
    """
    self.ret = []
    if root is None:
        return self.ret
    s = []
    self.binaryTreePathsRec(root,s)
    return self.ret


def binaryTreePathsRec(self,root,s):
    if root is None:
        return
    s.append(str(root.val))
    if root.left is None and root.right is None:
        self.ret.append('->'.join(s))
    else:
        self.binaryTreePathsRec(root.left,s)
        self.binaryTreePathsRec(root.right,s)
    s.pop()