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HomeLeetCode ProblemsKth Smallest Path XOR Sum
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How to Solve Kth Smallest Path XOR Sum Problem

Master the Kth Smallest Path XOR Sum LeetCode problem with undetectable real-time assistance. Get instant solutions and explanations during your coding interviews.

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Hard#3590
LeetCode Problem

Kth Smallest Path XOR Sum

You are given an undirected tree rooted at node 0 with n nodes numbered from 0 to n - 1. Each node i has an integer value vals[i], and its parent is given by par[i]. The path XOR sum from the root to a node u is defined as the bitwise XOR of all vals[i] for nodes i on the path from the root node to node u, inclusive. You are given a 2D integer array queries, where queries[j] = [uj, kj]. For each query, find the kjth smallest distinct path XOR sum among all nodes in the subtree rooted at uj. If there are fewer than kj distinct path XOR sums in that subtree, the answer is -1. Return an integer array where the jth element is the answer to the jth query. In a rooted tree, the subtree of a node v includes v and all nodes whose path to the root passes through v, that is, v and its descendants.

ArrayTreeDepth-First SearchOrdered Set

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Problem Breakdown

Understanding the Kth Smallest Path XOR Sum Problem

Let's break down this LeetCode problem and understand what makes it challenging in interview settings.

Problem Statement

You are given an undirected tree rooted at node 0 with n nodes numbered from 0 to n - 1. Each node i has an integer value vals[i], and its parent is given by par[i]. The path XOR sum from the root to a node u is defined as the bitwise XOR of all vals[i] for nodes i on the path from the root node to node u, inclusive. You are given a 2D integer array queries, where queries[j] = [uj, kj]. For each query, find the kjth smallest distinct path XOR sum among all nodes in the subtree rooted at uj. If there are fewer than kj distinct path XOR sums in that subtree, the answer is -1. Return an integer array where the jth element is the answer to the jth query. In a rooted tree, the subtree of a node v includes v and all nodes whose path to the root passes through v, that is, v and its descendants.

HardProblem #3590
LeetCode

Kth Smallest Path XOR Sum

Related Topics

ArrayTreeDepth-First SearchOrdered Set

How PhantomCodeAI Helps

Get real-time assistance for Kth Smallest Path XOR Sum problems during coding interviews. PhantomCodeAI provides instant solutions and explanations.

Examples

# Example 1

Input
par = [-1,0,0], vals = [1,1,1], queries = [[0,1],[0,2],[0,3]]
Output
[0,1,-1]

# Example 2

Input
par = [-1,0,1], vals = [5,2,7], queries = [[0,1],[1,2],[1,3],[2,1]]
Output
[0,7,-1,0]

Constraints

1 <= n == vals.length <= 5 * 104
0 <= vals[i] <= 105
par.length == n
par[0] == -1
0 <= par[i] < n for i in [1, n - 1]
1 <= queries.length <= 5 * 104
queries[j] == [uj, kj]
0 <= uj < n
1 <= kj <= n
The input is generated such that the parent array par represents a valid tree.

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Solve Kth Smallest Path XOR Sum — You are given an undirected tree rooted at node 0 with n nodes numbered from 0 t...

Here's the optimal approach using Array:

def solve(input):
# Optimal O(n) solution
return result

Time: O(n)  |  Space: O(n)

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Undetectability Checklist

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Undetectability and technical details

Our native desktop architecture avoids common detection vectors used by browser extensions. We provide a clear checklist so you can run basic checks and confirm the app will be invisible.

Platform compatibility and limitations

We work with Zoom, HackerRank, CodeSignal, CoderPad and other web-based platforms. Check the compatibility note and request a browser link if a specific desktop app is unsupported.

Frequently Asked Questions

Common questions about solving Kth Smallest Path XOR Sum and using PhantomCodeAI during coding interviews.

How does PhantomCodeAI help with LeetCode problems during a coding interview?
PhantomCodeAI reads the problem from a screenshot or listens to it via audio, then generates a complete solution with a step-by-step approach and time/space complexity, so you can focus on explaining your reasoning rather than getting stuck on implementation.
Which programming languages does PhantomCodeAI support?
11 languages including Python, Java, C++, JavaScript, TypeScript, Go, Rust, Ruby, Swift, Kotlin, and C#. Set a preferred language to get idiomatic solutions.
Does PhantomCodeAI work with HackerRank, CodeSignal, and CoderPad?
Yes — it works alongside LeetCode, HackerRank, CodeSignal, CoderPad, and HackerEarth, plus any browser-based coding environment.
Can PhantomCodeAI handle follow-up questions and modifications?
Yes. Capture the modified problem by screenshot or audio and get an updated solution within seconds, including new edge cases and optimizations.
Is PhantomCodeAI detectable during live interviews?
PhantomCodeAI runs as a native desktop overlay that does not appear in screen shares, recordings, or proctoring software, and works with Zoom, Google Meet, Microsoft Teams, and major coding platforms.
Should I still practice these problems on my own first?
Yes. The most durable preparation is solving problems unaided first, then using AI afterward to review your approach, complexity, and missed edge cases — use it to debrief and learn, not to skip the reps.

Related LeetCode Problems

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