Binary Tree Right Side View
Created: September 13, 2018 by [lek-tin]
Last updated: September 13, 2018
Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
Example
Input: [1,2,3,null,5,null,4]
Output: [1, 3, 4]
Explanation:
1 <---
/ \
2 3 <---
\ \
5 4 <---
Solution
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def rightSideView(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
res = []
def pick(root, level):
if root != None:
if level == len(res):
res.append(root.val)
pick(root.right, level + 1)
pick(root.left, level + 1)
pick(root, 0)
return res
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def rightSideView(self, root):
"""
:type root: TreeNode
:rtype: List[int]
"""
res = []
self.iterate(res, root, 0)
return res
def iterate(self, res, node, level):
if node == None:
return
if len(res) == level:
res.append(node.val)
else:
res[level] = node.val
if node.left:
self.iterate(res, node.left, level+1)
if node.right:
self.iterate(res, node.right, level+1)
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def rightSideView(self, root: TreeNode) -> List[int]:
res = []
self.helper(root, res, 0)
return res
def helper(self, root, res, level):
if not root:
return
if len(res) <= level:
res.append(root.val)
self.helper(root.right, res, level+1)
self.helper(root.left, res, level+1)