170. Two Sum III - Data structure design

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Problem

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.

Example 1:

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

Example 2:

add(3); add(1); add(2);
find(3) -> true
find(6) -> false

Code

class TwoSum {
    private HashMap<Integer, Integer> map;
    /** Initialize your data structure here. */
    public TwoSum() {
        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(Map.Entry<Integer, Integer> entry : map.entrySet()){
            int num1 = entry.getKey();
            int comp = value - num1;
            if((num1 == comp) && entry.getValue() > 1
              || (num1 != comp) && map.containsKey(comp)){
                return true;
            }
        }

        return false;
    }
}

/**
 * Your TwoSum object will be instantiated and called as such:
 * TwoSum obj = new TwoSum();
 * obj.add(number);
 * boolean param_2 = obj.find(value);
 */