Day 37.2.txt

1207. Unique Number of Occurrences

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 {
    public boolean uniqueOccurrences(int[] a) {
        HashMap<Integer,Integer> nm=new HashMap<>();
        int i;
        for(i=0;i<a.length;i++)
        {
            if(nm.containsKey(a[i]))
                nm.put(a[i] , nm.get(a[i])+1);
            else
                nm.put(a[i],1);
        }
        Set<Integer> kk=new HashSet<>(nm.values());
        return kk.size()==nm.size();
    }
}