Leetcode 1207. Unique Number of Occurrences

1207. Unique Number of Occurrences

難易度

EASY

アプローチ

HashMap, HashSet

class Solution {
    public boolean uniqueOccurrences(int[] arr) {
        
        HashMap<Integer, Integer> hashMap = new HashMap<>();
        HashSet<Integer> set = new HashSet<>();
        for(int i : arr){
            hashMap.put(i, hashMap.getOrDefault(i,0) + 1);
        }

        for (Map.Entry<Integer,Integer> a: hashMap.entrySet()) {
            if(set.contains(a.getValue())){
                return false;
            }
            set.add(a.getValue());
        }
        
        return true;
    }
}