1 class TwoSum {
 2
 3     HashMap<Integer, Integer> hm;
 4
 5     /** Initialize your data structure here. */
 6     public TwoSum() {
 7         hm = new HashMap<Integer, Integer>();
 8     }
 9
10     /** Add the number to an internal data structure.. */
11     public void add(int number) {
12         hm.put(number, hm.getOrDefault(number, 0) + 1);
13     }
14
15     /** Find if there exists any pair of numbers which sum is equal to the value. */
16     public boolean find(int value) {
17         for(Map.Entry<Integer, Integer> entry : hm.entrySet()){
18             int num1 = entry.getKey();
19             int num2 = value-num1;
20             if(hm.containsKey(num2) && (hm.get(num2)>1 || num1!=num2)){
21                 return true;
22             }
23         }
24         return false;
25     }
26 }
27
28 /**
29  * Your TwoSum object will be instantiated and called as such:
30  * TwoSum obj = new TwoSum();
31  * obj.add(number);
32  * boolean param_2 = obj.find(value);
33  */

 1 public class TwoSum {
 2     HashSet<Integer> nums;
 3     HashSet<Integer> sums;
 4
 5     /** Initialize your data structure here. */
 6     public TwoSum() {
 7         nums = new HashSet<Integer>();
 8         sums = new HashSet<Integer>();
 9     }
10
11     /** Add the number to an internal data structure.. */
12     public void add(int number) {
13         Iterator<Integer> it = nums.iterator();
14         while(it.hasNext()){
15             sums.add(it.next()+number);
16         }
17         nums.add(number);
18     }
19
20     /** Find if there exists any pair of numbers which sum is equal to the value. */
21     public boolean find(int value) {
22         return sums.contains(value);
23     }
24 }
25
26 /**
27  * Your TwoSum object will be instantiated and called as such:
28  * TwoSum obj = new TwoSum();
29  * obj.add(number);
30  * boolean param_2 = obj.find(value);
31  */