using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        int[] arr = new int[10] { 3, 5, 1,3,4,5,6,7,8, 2 };

        foreach(Tuple<int,int> r in getSubarrayInsideRange(arr, 8, 15)) {

            Console.WriteLine(r.Item1 + " " + r.Item2); 

        }

        Console.WriteLine("Hello World");

    }

    // this is not right, not counting all possibilities or keeping track of indices

    public static List<Tuple<int,int>> getSubarrayInsideRange(int[] arr, int low, int high) {

        List<Tuple<int, int>> result = new List<Tuple<int, int>>();

        Array.Sort(arr);

        int i =0, j=1;

        int sum = arr[i] + arr[j];

        while(i < arr.Length || j < arr.Length) {

            if (low < sum  && high > sum) {

                result.Add(new Tuple<int, int> (i, j));

            }

            if (sum >= high) { sum -= arr[i]; i++; }

            if (sum <= low) { sum += arr[j]; j++; }

        }

        return result;

    }

}