Binary Tree Paths

Problem: Binary Tree Paths

We can use depth-first search to solve this problem. We need to pass operating path result as parameter of helper function. Once we reach a leaf node, we append the leaf node to our result and return it.

Code in Python:

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

class Solution(object):
    def binaryTreePaths(self, root):
        """
        :type root: TreeNode
        :rtype: List[str]
        """
        ans = []
        if not root: return []
        def dfs(node, string):
            if not node.left and not node.right: ans.append(string+str(node.val))
            if node.left: dfs(node.left, string+str(node.val)+"->")
            if node.right: dfs(node.right, string+str(node.val)+"->")
        dfs(root, "")
        return ans