int threeSumClosest(vector<int> &numbers, int target) {
    // write your code here
    if (numbers.size() < 3) return 0;

    int closestSum = INT_MAX;
    sort(numbers.begin(), numbers.end());
    for (int i=0; i<numbers.size()-2; i++) {
        int left = i+1;
        int right = numbers.size()-1;

        while (left < right) {
            int sum = numbers[i] + numbers[left] + numbers[right];
            if (sum == target) {
                return target;
            } else if (sum < target) {
                left += 1;
            } else {
                right -= 1;
            }

            if (abs(target - sum) < abs(target - closestSum)) {
                closestSum = sum;
            }
        }
    }

    return closestSum;
}