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How to Solve Find Occurrences of an Element in an Array Problem
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Start Free for WindowsMedium#3159
LeetCode ProblemFind Occurrences of an Element in an Array
You are given an integer array nums, an integer array queries, and an integer x. For each queries[i], you need to find the index of the queries[i]th occurrence of x in the nums array. If there are fewer than queries[i] occurrences of x, the answer should be -1 for that query. Return an integer array answer containing the answers to all queries.
ArrayHash Table
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Problem Breakdown
Understanding the Find Occurrences of an Element in an Array Problem
Let's break down this LeetCode problem and understand what makes it challenging in interview settings.
Problem Statement
You are given an integer array nums, an integer array queries, and an integer x. For each queries[i], you need to find the index of the queries[i]th occurrence of x in the nums array. If there are fewer than queries[i] occurrences of x, the answer should be -1 for that query. Return an integer array answer containing the answers to all queries.
MediumProblem #3159
LeetCodeFind Occurrences of an Element in an Array
Related Topics
ArrayHash Table
How Phantom Code Helps
Get real-time assistance for Find Occurrences of an Element in an Array problems during coding interviews. Phantom Code provides instant solutions and explanations.
Examples
# Example 1
Input
nums = [1,3,1,7], queries = [1,3,2,4], x = 1
Output
[0,-1,2,-1]
# Example 2
Input
nums = [1,2,3], queries = [10], x = 5
Output
[-1]
Constraints
1 <= nums.length, queries.length <= 105
1 <= queries[i] <= 105
1 <= nums[i], x <= 104
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Solve Find Occurrences of an Element in an Array — You are given an integer array nums, an integer array queries, and an integer x....
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Frequently Asked Questions
Common questions about solving Find Occurrences of an Element in an Array and using Phantom Code during coding interviews.
How does Phantom Code help me solve coding problems like Find Occurrences of an Element in an Array 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 Find Occurrences of an Element in an Array?
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 Find Occurrences of an Element in an Array?
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 Find Occurrences of an Element in an Array 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 Find Occurrences of an Element in an Array 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 Find Occurrences of an Element in an Array 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 Find Occurrences of an Element in an Array 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 Find Occurrences of an Element in an Array 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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