Задача: Комбинированная сумма

CombinationSum.cs

using System;
using System.Linq;
using System.Collections.Generic;
					
public class Program
{
	private static int Target;
	public static IList<IList<int>> Output;

	public static IList<IList<int>> CombinationSum(int[] candidates, int target) {
		Array.Sort(candidates);
		Target = target;
		Output = new List<IList<int>>();

		Backtracking(candidates, new List<int>(), 0, 0);

		return Output;
	}

	public static void Backtracking(int[] input, List<int> curr, int index, int sum)
	{   
		if (sum > Target)
		{
		    return;
		}

		if (sum == Target) {
		    Output.Add(new List<int>(curr));
		    return;
		}

		for (int i = index; i < input.Length; i++)
		{
		    if (i > index && input[i] == input[i - 1])
			continue; // пропускаем дубликаты

		    curr.Add(input[i]);

		    Backtracking(input, curr, i + 1, sum + input[i]);

		    curr.RemoveAt(curr.Count - 1);
		}
	}
	
	private static void ShowListOfList(IList<IList<int>> list)
	{
		Console.WriteLine($"[{string.Join(", ", list.Select(x => "[" + string.Join(", ", x) + "]"))}]");
	}
	
	public static void Main()
	{
		Console.WriteLine("UniLecs");
		
		// tests
		ShowListOfList(CombinationSum(new int[] { 2,5,2,1,2 }, 5)); // [[1, 2, 2], [5]]
		ShowListOfList(CombinationSum(new int[] { 10,1,2,7,6,1,5 }, 8)); // [[1, 1, 6], [1, 2, 5], [1, 7], [2, 6]]
	}
}