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DSA · Hashing · #20

Contains Duplicate

Module 23 · difficulty 1/5·⏱ 30:00starts on first keystroke

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

Examples
  • nums = [1,2,3,1] → true
  • nums = [1,2,3,4] → false
  • nums = [1,1,1,3,3,4,3,2,4,2] → true

Stuck? Reveal an animated walkthrough of the approach.

Constraints
  • · 1 <= nums.length <= 10^5
  • · -10^9 <= nums[i] <= 10^9
Session phases
A · Clarify
B · Approach
C · Complexity
D · Edges
E · Code
F · Tradeoff
G · Score
Phase A — Clarify
Ask questions about input bounds, types, and edge constraints.
Ask the coach clarifying questions about the problem.
When you've covered this phase, advance to the next.