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How to Solve Recover a Tree From Preorder Traversal Problem
Master the Recover a Tree From Preorder Traversal LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.
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Start Free for WindowsHard#1028
LeetCode ProblemRecover a Tree From Preorder Traversal
We run a preorder depth-first search (DFS) on the root of a binary tree. At each node in this traversal, we output D dashes (where D is the depth of this node), then we output the value of this node. If the depth of a node is D, the depth of its immediate child is D + 1. The depth of the root node is 0. If a node has only one child, that child is guaranteed to be the left child. Given the output traversal of this traversal, recover the tree and return its root.
StringTreeDepth-First SearchBinary Tree
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Problem Breakdown
Understanding the Recover a Tree From Preorder Traversal Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
We run a preorder depth-first search (DFS) on the root of a binary tree. At each node in this traversal, we output D dashes (where D is the depth of this node), then we output the value of this node. If the depth of a node is D, the depth of its immediate child is D + 1. The depth of the root node is 0. If a node has only one child, that child is guaranteed to be the left child. Given the output traversal of this traversal, recover the tree and return its root.
HardProblem #1028
LeetCodeRecover a Tree From Preorder Traversal
Related Topics
StringTreeDepth-First SearchBinary Tree
How Phantom Code Helps
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Examples
# Example 1
Input
traversal = "1-2--3--4-5--6--7"
Output
[1,2,5,3,4,6,7]
# Example 2
Input
traversal = "1-2--3---4-5--6---7"
Output
[1,2,5,3,null,6,null,4,null,7]
# Example 3
Input
traversal = "1-401--349---90--88"
Output
[1,401,null,349,88,90]
Constraints
The number of nodes in the original tree is in the range [1, 1000].
1 <= Node.val <= 109
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Solve Recover a Tree From Preorder Traversal — We run a preorder depth-first search (DFS) on the root of a binary tree. At each...
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def solve(input):
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Frequently Asked Questions
Common questions about solving Recover a Tree From Preorder Traversal and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Recover a Tree From Preorder Traversal during interviews?
Phantom Code generates complete solutions instantly with proper complexity analysis, letting you focus on explaining your approach and demonstrating problem-solving skills rather than getting stuck on implementation details during high-pressure situations.
What if the interviewer asks follow-up questions or modifications to problems like Recover a Tree From Preorder Traversal?
Phantom Code adapts in real-time. Screenshot the modified problem or use audio mode to capture the interviewer's follow-up, and get an updated solution within seconds — including edge cases and optimizations.
Can Phantom Code help me communicate my solution for problems like Recover a Tree From Preorder Traversal?
Yes. Phantom Code provides step-by-step approach explanations with 3 progressive thoughts, so you can walk through your solution naturally. It also provides time and space complexity analysis to discuss trade-offs.
How does Phantom Code assist with different programming languages for Recover a Tree From Preorder Traversal type problems?
Phantom Code supports 11 programming languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set your preferred language and get idiomatic solutions.
What coding mistakes does Phantom Code help me avoid during Recover a Tree From Preorder Traversal interviews?
Phantom Code catches common mistakes like off-by-one errors, missing edge cases, incorrect base conditions, and suboptimal approaches. It provides clean, well-structured code that handles all edge cases.
Is Phantom Code detectable when solving problems like Recover a Tree From Preorder Traversal during live interviews?
No. Phantom Code runs as an invisible desktop overlay that doesn't appear in screen shares, recordings, or proctoring software. It works with Zoom, HackerRank, CodeSignal, CoderPad, and all major platforms.
How does Phantom Code help when I'm struggling with Recover a Tree From Preorder Traversal style questions under pressure?
The AI provides structured guidance: first the approach (what algorithm/data structure to use and why), then the implementation with clean code, and finally complexity analysis. This helps you think clearly even under pressure.
Does Phantom Code work for the coding platforms used in Recover a Tree From Preorder Traversal interviews?
Yes. Phantom Code works with all major coding platforms including LeetCode, HackerRank, CodeSignal, CoderPad, HackerEarth, and any browser-based coding environment.
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