315. Unique Number of Occurrences
Easy
Frequency Uniqueness
Hashing
Problem
Given an array of integers arr, return true if the number of occurrences of every distinct value is unique. Otherwise return false.
Examples
Example 1
Input: [1,2,2,1,1,3]
Output: true
Example 2
Input: [1,2]
Output: false
Example 3
Input: [-3,0,1,-3,1,1,1,-3,10,0]
Output: true
Constraints
� 1 <= arr.length <= 1000
� -1000 <= arr[i] <= 1000
Hints
?? First compute the frequency of each value.
?? Then determine whether any two values have the same frequency.
?? A set of frequencies makes the second step simple.
Expected Complexity
Time: O(n)
Space: O(n)
Follow-up
Can you solve it without sorting the frequencies?
Practice Notes
Attempts: 0
Time spent: 0min
Hints used: 0
JavaScript
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Case 1
Case 2
Case 3
Input
[1,2,2,1,1,3]Expected
true