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257.binary-tree-paths.py
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48 lines (44 loc) · 1.15 KB
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# Tag: String, Backtracking, Tree, Depth-First Search, Binary Tree
# Time: O(N)
# Space: O(H)
# Ref: -
# Note: -
# Given the root of a binary tree, return all root-to-leaf paths in any order.
# A leaf is a node with no children.
#
# Example 1:
#
#
# Input: root = [1,2,3,null,5]
# Output: ["1->2->5","1->3"]
#
# Example 2:
#
# Input: root = [1]
# Output: ["1"]
#
#
# Constraints:
#
# The number of nodes in the tree is in the range [1, 100].
# -100 <= Node.val <= 100
#
#
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, val=0, left=None, right=None):
# self.val = val
# self.left = left
# self.right = right
class Solution:
def binaryTreePaths(self, root: Optional[TreeNode]) -> List[str]:
res = []
self.dfs(root, str(root.val), res)
return res
def dfs(self, node: TreeNode, tmp: list, res: list):
if node.left is None and node.right is None:
res.append(tmp)
return
for child in [node.left, node.right]:
if child is not None:
self.dfs(child, tmp + "->" + str(child.val), res)