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Top 50 deduplication Interview Questions

The most frequently asked deduplication questions across all roles and companies, ranked by real interview frequency. Updated daily.

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1
CodingStart here. 48 questions · ~1190 min
Programming Languages FamiliarityEasy
Practice
Recently asked

Remove duplicate language names while preserving the order in which they were provided.

Hash TablesdeduplicationCodingBrickred SystemsRTXRender
Three Sum Unique TripletsHard
Practice
Recently asked

Find all unique zero-sum triplets by sorting the array and applying two pointers in O(n²) time.

deduplicationArraysSortingSaviyntIISS STOXXGGoHighLevel
Finding Duplicates in an ArrayMedium
Practice
Recently asked

Use a hash set to find each duplicated array value once in O(n) time.

Hash TablesdeduplicationArraysAutomatic Data ProcessingADPArrow International
Longest Substring Without RepeatsMedium
Practice
Recently asked

Use a sliding window and hash map to find the longest substring with no repeated characters in O(n) time.

deduplicationleetcodeArraysBBeaconfiresolutionPrime VideoTTestMu AI
Caching LLM Calls for Dynamic QueriesHard
Practice
Recently asked

Build an LRU cache that reuses exact or semantically similar LLM responses while enforcing TTL and relevance thresholds.

deduplicationcachingcacheMMiracle-EarCCYOS SolutionsFactset
Remove Duplicates from ListEasy
Practice
Recently asked

Remove repeated values from a Samsung Semiconductor linked list in place using a runner pointer and constant extra space.

deduplicationLinked ListsSamsung SemiconductorImpact Recruitment GroupRakuten Advertising
Remove Duplicates From ArrayEasy
Practice
Recently asked

Remove duplicate values from an array while preserving the order of their first occurrences.

Hash TablesdeduplicationArraysRealpageBirlasoftCCEVA
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2
More topics2 questions · ~50 min
SQL Duplicate Record CleanupMedium
Practice
Recently asked

Identify duplicate transaction rows, retain the earliest record, and delete later duplicates safely.

deduplicationdata cleaningtransactionsOracleAmexBrooksource
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Hands-on SQL practiceWrite and run real queries in the editor. 1 drill · ~10 min
The finish line: interview-readyComplete all 50 questions plus 1 hands-on drill to finish this plan.