1207. Unique Number of Occurrences

class Solution {
    public boolean uniqueOccurrences(int[] arr) {
        Map<Integer,Integer> mp = new HashMap<>();
           int frq[] = new int[arr.length+1];
           
           for (int i = 0; i < arr.length; i++) 
               mp.put(arr[i], mp.getOrDefault(arr[i], 0)+1);
           
           for (Map.Entry<Integer, Integer> entry : mp.entrySet()) 
               frq[entry.getValue()]++;
           
           for (int i = 0; i < frq.length; i++) 
               if(frq[i] > 1) return false;
           
           return true;
    }
}