[LeetCode] Two Sum III - Data structure Design

Problem Description:
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) -> truefind(7) -> false
Well, the basic idea is simple: just store the added numbers in an internal data structure. When we are asked to find a sum, we just iterate over all the numbers in the internal data structure. For each number num, if sum - num is also in the data structurue and not at the same "position"as num, then return true. After iterating over all num and we have not returnred true, return false. The key to an efficient implementation lies in what data structure to store the added numbers. Since there may be duplicate numbers, personally I think using an unordered_map is a nice choice. It uses num as key and its number of appearances as value. It enalbes both O(1) insertion and O(1) query, and thus O(1) for add and O(n) for find if there are n elements in total.
Now comes the following code.

 1 /**
 2 Design and implement a TwoSum class. It should support the following operations: add and find.
 3 
 4 add - Add the number to an internal data structure.
 5 find - Find if there exists any pair of numbers which sum is equal to the value.
 6 
 7 For example,
 8 
 9 add(1); add(3); add(5);
10 find(4) -> true
11 find(7) -> false
12 */
13 
14 #include <iostream>
15 #include <unordered_map>
16 
17 using namespace std;
18 
19 class twoSum {
20 public:
21     twoSum(void);
22     ~twoSum(void);
23 
24     void add(int);
25     bool find(int);
26 private:
27     unordered_map<int, int> data;
28 };
29 
30 twoSum::twoSum(void) {
31     data.clear();
32 }
33 
34 twoSum::~twoSum(void) {
35     data.clear();
36 }
37 
38 void twoSum::add(int num){
39     data[num]++;
40 }
41 
42 bool twoSum::find(int sum) {
43     for (auto nums : data) {
44         int num = nums.first;
45         int counts = nums.second;
46         int another = sum - num;
47         if ((another == num && counts > 1) || (another != num && data.find(another) != data.end()))
48             return true;
49     }
50     return false;
51 }
52 
53 void twoSumTest(void) {
54     twoSum ts = twoSum();
55     ts.add(1);
56     ts.add(3);
57     ts.add(5);
58     printf("Computed: ");
59     for (int sum = 1; sum <= 10; sum++)
60         printf("%d, ", ts.find(sum));
61     printf("
");
62     printf("Expected: 0, 0, 0, 1, 0, 1, 0, 1, 0, 0.
");
63 }
64 
65 int main(void) {
66     twoSumTest();
67     system("pause");
68     return 0;
69 }

If you run this code, you may obtain the following result (I run it in Microsoft Visual Studio Professional 2012).

Computed: 0, 0, 0, 1, 0, 1, 0, 1, 0, 0,
Expected: 0, 0, 0, 1, 0, 1, 0, 1, 0, 0.

Well, since I have not bought these extra problems, I can only obtain the problem description from the web. So I am not quite clear about the interface of the provided Solution class. I just try to implement my code and test it based on my understanding of the problem description. Moreover, I am unable to test my code on the online judge and so my code may go wrong. If you have access to these problems and feel like trying my solution, please tell me about the result. Thank you very much!