题解 | 不同的体重

import java.util.*;


public class Solution {
    public boolean uniqueOccurrences (int[] arr) {
        final int n = arr.length;
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < n; ++i) {
            map.merge(arr[i], 1, Integer::sum);
        }
        Set<Integer> set = new HashSet<>();
        for (Integer i : map.values()) {
            if (set.contains(i)) {
                return false;
            } else {
                set.add(i);
            }
        }
        return true;
    }
}