A recursive algorithm to find two integers in an array that sums to a given integer

Question

I need an algorithm to determine if an array contains two elements that sum to a given integer.

The array is sorted.

The algorithm should be recursiv

Answer 1

You can convert any iterative algorithm into a recursive one by using (for instance) tail recursion. I'd be more expansive, if it weren't homework. I think you'll understand it from the other post.

Answer 2

Here is my solution: I iterate until the first number is greater than the expected sum, then until to second one or the sum of two is greater than the expected sum. If I do not want a correct answer, I return {-1,-1} (assuming all numbers are positive integers)

{

private static int[] sumOfTwo(int[] input, int k) {
    for (int i = 0; i < input.length - 1; i++) {
        int first = input[i];
        for (int j = 1; j < input.length; j++) {
            int second = input[j];
            int sum = first + second;
            if (sum == k) {
                int[] result = {first, second};
                return result;
            }
            if (second > k || sum > k) {
                break;
            }
        }
        if (first > k) {
            break;
        }
    }
    int[] begin = {-1, -1};
    return begin;
}

}