EasyNo. 2689LeetCode Premium
Extract Kth Character From The Rope Tree — LeetCode 2689 Python Solution
- Pattern
- Tree Traversal
- Topics
- Tree, Depth-First Search, Binary Tree
- Reading time
- 3 min
- Source
- leetcode.com
The problem
You are given the root of a binary tree and an integer k. Besides the left and right children, every node of this tree has two other properties, a string node.val containing only lowercase English letters (possibly empty) and a non-negative integer node.len.
Example
- Input
- root = [10,4,"abcpoe","g","rta"], k = 6
- Output
- "b"
- Explanation
- In the picture below, we put an integer on internal nodes that represents node.len, and a string on leaf nodes that represents node.val.
Python solution
# Definition for a rope tree node.
# class RopeTreeNode(object):
# def __init__(self, len=0, val="", left=None, right=None):
# self.len = len
# self.val = val
# self.left = left
# self.right = right
class Solution:
def getKthCharacter(self, root: Optional[object], k: int) -> str:
def dfs(root):
if root is None:
return ""
if root.len == 0:
return root.val
return dfs(root.left) + dfs(root.right)
return dfs(root)[k - 1]Complexity
- Time
- O(V+E)
- Space · auxiliary
- O(V)
Pattern: Tree Traversal
Choose the order — preorder, inorder, postorder, level — and the problem solves itself. LeetCode 2689. Extract Kth Character From The Rope 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
| No. | Problem | Difficulty |
|---|---|---|
| 0098 | Validate Binary Search Tree | Medium |
| 0099 | Recover Binary Search Tree | Medium |
| 0100 | Same Tree | Easy |
| 0101 | Symmetric Tree | Easy |
| 0104 | Maximum Depth of Binary Tree | Easy |
| 0110 | Balanced Binary Tree | Easy |
Frequently asked questions
- How hard is LeetCode 2689. Extract Kth Character From The Rope Tree?
LeetCode 2689. Extract Kth Character From The Rope Tree is rated Easy on LeetCode.
- What is the time complexity of LeetCode 2689. Extract Kth Character From The Rope Tree?
The Python solution on this page runs in O(V+E).
- What is the space complexity of LeetCode 2689. Extract Kth Character From The Rope Tree?
The Python solution on this page uses O(V) auxiliary space.
- What topics does LeetCode 2689. Extract Kth Character From The Rope Tree cover?
LeetCode 2689. Extract Kth Character From The Rope Tree is tagged Tree, Depth-First Search and Binary Tree on LeetCode.
- Is LeetCode 2689. Extract Kth Character From The Rope Tree a premium problem?
Yes. LeetCode 2689. Extract Kth Character From The Rope Tree is a LeetCode Premium problem, so the full statement and test cases require a paid LeetCode subscription.