EASY NC#1 Blind #3 Arrays & Hashing

217. Contains Duplicate

📖 Problem

Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.

🧠 Visual Learning Aid

1 Model the input into the right structure
2 Choose the core technique and invariant
3 Execute step-by-step with a sample
4 Validate complexity and edge cases

JS/TS Refreshers

  • •Array methods (`push`, `pop`, `shift`, `slice`)
  • •Object/Map/Set usage patterns
  • •Function parameter and return typing

Logical Thinking Concepts

  • •Define invariants before coding
  • •Check edge cases first (`[]`, single element, duplicates)
  • •Estimate time/space before implementation

💡 Approach

  • → Use Set for O(1) lookups
  • → Compare Set size with array length
  • → Time: O(n), Space: O(n)

🛠️ Hints & Pitfalls

Hints

  • •Use Set for O(1) lookups
  • •Compare Set size with array length
  • •Time: O(n), Space: O(n)

🧪 Test Cases

Hidden tests on submit: 3

Test Case 1
Not run
Input:
containsDuplicate([1, 2, 3, 1]);
Expected:
true
Test Case 2
Not run
Input:
containsDuplicate([1, 2, 3, 4]);
Expected:
false
Test Case 3
Not run
Input:
containsDuplicate([]);
Expected:
false

📝 Code Editor

📚 Reference Solution

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🔗 Related Problems

#1 Two Sum #36 Valid Sudoku #49 Group Anagrams #128 Longest Consecutive Sequence #238 Product of Array Except Self
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