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

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.

Have you met this question in a real interview?

Yes

Example

add(1); add(3); add(5);
find(4) // return true
find(7) // return false

class TwoSum {
    unordered_multiset<int> nums;
public:

    // Add the number to an internal data structure.
    void add(int number) {
        // Write your code here
        nums.insert(number);
    }

    // Find if there exists any pair of numbers which sum is equal to the value.
    bool find(int value) {
        // Write your code here
        for (int num : nums) {
            int count = (num == value - num) ? 2 : 1;
            if (nums.count(value - num) >= count) {
                return true;
            }
        }
        return false;
    }
};


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