1207-Unique-Number-of-Occurences.py

'''
Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique.

 

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

'''
class Solution:
    def uniqueOccurrences(self, arr: List[int]) -> bool:
        d = {}
        for i in range(len(arr)):
            d[arr[i]] = d.get(arr[i],0) + 1
        s = set()
        for i,j in d.items():
            if j in s:
                return False
            s.add(j)
        return True