Remove Duplicates from Sorted Array

Solution walkthrough for remove duplicates from sorted array with code and practical use cases.

Easy1 min read
Lookup / Frequency / MatchingHash Map

What This Problem Is Asking

In one sentence

Identify the core operation required by the prompt and produce the expected output efficiently.

Full problem statement

Remove Duplicates from Sorted Array

Given an integer array nums sorted in non-decreasing order, remove duplicates **in-place** so that each distinct value appears at most once. The relative order of the elements should be kept the same.

Return k after placing the final result in the first k slots of nums.

Recognition Clues

Signals that this pattern likely applies.

  • You need fast lookup while iterating once.
  • You are asked for indices, pairs, or direct matches.

Why This Pattern Fits

This pattern minimizes repeated scanning and keeps lookup decisions close to the traversal.

Daily usefulness: Useful in data validation, filtering, and UI state transformations encountered in daily product work.

Interview usefulness: This pattern appears frequently in screening rounds due to its clarity and optimization tradeoffs.

Real-world relevance: Maps to production concerns like deduplication, lookup acceleration, and ranking support.

Code Snippets

Swift

Practical Use Cases

  • Resolve complementary value lookups in near real-time APIs.
  • Detect matching pairs in transactional or telemetry streams.
  • Use hash-map pairing logic in data validation pipelines.

Demo Ideas

Interactive ways to teach this algorithm.

  • Animate lookup table growth while scanning inputs.
  • Visualize when candidate matches become valid outputs.

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