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

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public class TwoSum {
   
    HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();
   
public void add(int number) {
        if (map.containsKey(number)) {
            map.put(number, 2);
        } else {
            map.put(number, 1);
        }
}

public boolean find(int value) {
        for (Integer key : map.keySet()) {
            int v2 = value - key;
            if (v2 == key) return map.get(key) == 2;
            else {
                if (map.containsKey(v2)) {
                    return true;
                }
            }
        }
        return false;
}
}