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

Question

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

Python Solution

class Solution:
    def uniqueOccurrences(self, arr: List[int]) -> bool:
        d={}
        for i in arr:
            if i not in d:
                d[i]=1
            else:
                d[i]+=1
        s=set()
        for k,v in d.items():
            s.add(v)

        return (len(s)==len(d))