Find Nearest Right Node in Binary Tree — LeetCode 1602 Python Solution
MediumLeetCode PremiumTreeBreadth-First SearchBinary Tree
- Problem
- #1602
- Pattern
- Tree Traversal
- Reading time
- 3 min
- Source
- leetcode.com
The problem
Given the root of a binary tree and a node u in the tree, return the nearest node on the same level that is to the right of u, or return null if u is the rightmost node in its level.
Example
- Input
- root = [1,2,3,null,4,5,6], u = 4
- Output
- 5
- Explanation
- The nearest node on the same level to the right of node 4 is node 5.
Python solution
Python
# 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 findNearestRightNode(self, root: TreeNode, u: TreeNode) -> Optional[TreeNode]:
q = deque([root])
while q:
for i in range(len(q) - 1, -1, -1):
root = q.popleft()
if root == u:
return q[0] if i else None
if root.left:
q.append(root.left)
if root.right:
q.append(root.right)Complexity
| Measure | Complexity |
|---|---|
| Time | O(n) |
| Space | O(n) auxiliary |
Pattern: Tree Traversal
Choose the order — preorder, inorder, postorder, level — and the problem solves itself. LeetCode 1602. Find Nearest Right Node in Binary Tree is filed here because LeetCode tags it Tree and Binary Tree, which is the vocabulary this hub collects.
The tree traversal guide has the Python template for the pattern and the 225 LeetCode problems that use it.
Related problems
Frequently asked questions
- How hard is LeetCode 1602. Find Nearest Right Node in Binary Tree?
- LeetCode 1602. Find Nearest Right Node in Binary Tree is rated Medium on LeetCode.
- What is the time complexity of LeetCode 1602. Find Nearest Right Node in Binary Tree?
- The Python solution on this page runs in O(n).
- What is the space complexity of LeetCode 1602. Find Nearest Right Node in Binary Tree?
- The Python solution on this page uses O(n) auxiliary space.
- What topics does LeetCode 1602. Find Nearest Right Node in Binary Tree cover?
- LeetCode 1602. Find Nearest Right Node in Binary Tree is tagged Tree, Breadth-First Search and Binary Tree on LeetCode.
- Is LeetCode 1602. Find Nearest Right Node in Binary Tree a premium problem?
- Yes. LeetCode 1602. Find Nearest Right Node in Binary Tree is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.