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How to Solve Join Two Arrays by ID Problem
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Start Free for WindowsMedium#2722
LeetCode ProblemJoin Two Arrays by ID
Given two arrays arr1 and arr2, return a new array joinedArray. All the objects in each of the two inputs arrays will contain an id field that has an integer value. joinedArray is an array formed by merging arr1 and arr2 based on their id key. The length of joinedArray should be the length of unique values of id. The returned array should be sorted in ascending order based on the id key. If a given id exists in one array but not the other, the single object with that id should be included in the result array without modification. If two objects share an id, their properties should be merged into a single object:
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Problem Breakdown
Understanding the Join Two Arrays by ID Problem
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Problem Statement
Given two arrays arr1 and arr2, return a new array joinedArray. All the objects in each of the two inputs arrays will contain an id field that has an integer value. joinedArray is an array formed by merging arr1 and arr2 based on their id key. The length of joinedArray should be the length of unique values of id. The returned array should be sorted in ascending order based on the id key. If a given id exists in one array but not the other, the single object with that id should be included in the result array without modification. If two objects share an id, their properties should be merged into a single object:
MediumProblem #2722
LeetCodeJoin Two Arrays by ID
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How Phantom Code Helps
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Examples
# Example 1
Input
arr1 = [ {"id": 1, "x": 1}, {"id": 2, "x": 9} ], arr2 = [ {"id": 3, "x": 5} ]Output
[ {"id": 1, "x": 1}, {"id": 2, "x": 9}, {"id": 3, "x": 5} ]# Example 2
Input
arr1 = [ {"id": 1, "x": 2, "y": 3}, {"id": 2, "x": 3, "y": 6} ], arr2 = [ {"id": 2, "x": 10, "y": 20}, {"id": 3, "x": 0, "y": 0} ]Output
[ {"id": 1, "x": 2, "y": 3}, {"id": 2, "x": 10, "y": 20}, {"id": 3, "x": 0, "y": 0} ]# Example 3
Input
arr1 = [ {"id": 1, "b": {"b": 94},"v": [4, 3], "y": 48} ] arr2 = [ {"id": 1, "b": {"c": 84}, "v": [1, 3]} ]Output
[ {"id": 1, "b": {"c": 84}, "v": [1, 3], "y": 48} ]Constraints
arr1 and arr2 are valid JSON arrays
Each object in arr1 and arr2 has a unique integer id key
2 <= JSON.stringify(arr1).length <= 106
2 <= JSON.stringify(arr2).length <= 106
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Solve Join Two Arrays by ID — Given two arrays arr1 and arr2, return a new array joinedArray. All the objects ...
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Frequently Asked Questions
Common questions about solving Join Two Arrays by ID and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Join Two Arrays by ID 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 Join Two Arrays by ID?
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 Join Two Arrays by ID?
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 Join Two Arrays by ID 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 Join Two Arrays by ID 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 Join Two Arrays by ID 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 Join Two Arrays by ID 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 Join Two Arrays by ID 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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