170. Two Sum III - Data structure design

public class TwoSum {
    private HashMap<Integer, Integer> elements = new HashMap<Integer, Integer>();
 
    public void add(int number) {
        if (elements.containsKey(number)) {
            elements.put(number, elements.get(number) + 1);
        } else {
            elements.put(number, 1);
        }
    }
 
    public boolean find(int value) {
        for (Integer i : elements.keySet()) {
            int target = value - i;
            if (elements.containsKey(target)) {
                if (i == target && elements.get(target) < 2) {
                    continue;
                }
                return true;
            }
        }
        return false;
    }
}