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Top K Frequent Elements Mock Interview

  1. ✓Problem→
  2. 2Clarifying Questions→
  3. 3Constraints→
  4. 4Brute Force→
  5. 5Complexity Analysis→
  6. 6Pattern Recognition→
  7. 7Optimized Solution→
  8. 8Implementation→
  9. 9Testing→
  10. 10Follow-Up→
  11. 11Evaluation
Problem

Given an integer array nums and an integer k, return the k most frequent elements. The answer is guaranteed to be unique (no ties at the k-th position), and it may be returned in any order. Aim for a solution better than O(n log n).

Constraints
  • 1 ≤ n ≤ 10^5
  • -10^4 ≤ nums[i] ≤ 10^4
  • 1 ≤ k ≤ number of distinct elements
Example
in: nums = [1,1,1,2,2,3], k = 2
out: [1,2]

Clarify

Before choosing anything: what would you ask the interviewer? What assumptions are you making? (Duplicates? Empty input? Value ranges? What to return when there is no answer?)