Unique Number of Occurrences Coding Problem

Given an array of integers arr, return true if the number of occurrences of each value in the array is unique or false otherwise.

Example 1:

Input: arr = [1,2,2,1,1,3]
Output: true
Explanation: The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.

Example 2:

Input: arr = [1,2]
Output: false

Example 3:

Input: arr = [-3,0,1,-3,1,1,1,-3,10,0]
Output: true

Constraints:

1 <= arr.length <= 1000
-1000 <= arr[i] <= 1000

Solution:

class Solution {
    public boolean uniqueOccurrences(int[] arr) {
        Map<Integer, Integer> mp = new HashMap<>();
        Arrays.stream(arr).forEach(
            a -> mp.put(a, mp.getOrDefault(a, 0)+1)
        );
        long distinctCount = mp.values().stream().distinct().count();
        return distinctCount == mp.values().size();
    }
}

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