🧠 Before you code — what pattern fits?
Given an array of integers arr, return true if the number of occurrences of each value in the array is unique, or false otherwise.
[1,2,2,1,1,3] → true
[1,2] → false
🎬 Video explanation · Nick White
Your solution runs against 3 unit tests, including edge and large-value cases.
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Test console · 3 unit tests
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