170. Two Sum III - Data structure design

Design and implement a TwoSum class. It should support the following operations: add and find.

add - Add the number to an internal data structure. find - Find if there exists any pair of numbers which sum is equal to the value.

For example,

add(1); add(3); add(5);
find(4) -> true
find(7) -> false

public class TwoSum {
    Map<Integer, Integer> map = new HashMap<>();
    // Add the number to an internal data structure.
    public void add(int number) {
        if(map.containsKey(number)){
            map.put(number, map.get(number) + 1);
        }else{
            map.put(number, 1);
        }
    }

    // Find if there exists any pair of numbers which sum is equal to the value.
    public boolean find(int value) {
        for(Integer key : map.keySet()){
            int target = value -key;
            if(map.containsKey(target)){
                if(target == key && map.get(key) <2) continue;
                return true;
            }
        }
        return false;
    }
}


// Your TwoSum object will be instantiated and called as such:
// TwoSum twoSum = new TwoSum();
// twoSum.add(number);
// twoSum.find(value);