Algorithms - 03. Combinations with Repetition

using System;
using System.Linq;

namespace Algorithms
{
    class Program
    {
        static int k;
        static int[] combinations;
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            k = int.Parse(Console.ReadLine());

            combinations = new int[k];
            PrintCombinations(0, 1, n);
        }

        private static void PrintCombinations(int index, int start, int n)
        {
            if (index == k)
            {
                PrintSolution();
                return;
            }

            for (int i = start; i <= n; i++)
            {
                combinations[index] = i;
                PrintCombinations(index + 1, i, n);
            }
        }

        private static void PrintSolution()
        {
            Console.WriteLine(string.Join(" ", combinations)); ;
        }
    }
}