Leetcode 39 - combination sum - past all test cases

Leetcode39_CombinationSum_practice.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Leetcode39_CombinationSum
{
    class Leetcode39_CombinationSum
    {
        /*
         * understand the design issue: 
         * the bug to avoid: 
        Input:
        [2,3,6,7]
        7
        Output:
        [[2,2,3],[2,3,2],[3,2,2],[7]]
        Expected:
        [[2,2,3],[7]]
        */
        static void Main(string[] args)
        {
        }

        public IList<IList<int>> CombinationSum(int[] numbers, int target)
        {
            var subsets = new List<IList<int>>();
            var subset  = new List<int>();

            findSubsetWithSum(subsets, subset, numbers, target, 0);

            return subsets;
        }

        /// <summary>
        /// using recursive function to conduct depth first search
        /// </summary>
        /// <param name="allSubsets"></param>
        /// <param name="subset"></param>
        /// <param name="numbers"></param>
        /// <param name="remaining"></param>
        /// <param name="start"></param>
        private void findSubsetWithSum(
            IList<IList<int>> allSubsets, 
            IList<int> subset, 
            int[] numbers, 
            int   remaining, 
            int   start)
        {
            // boundary check - sum value
            if(remaining < 0) 
            {
                return;
            }

            // base case 
            if(remaining == 0)
            {
                allSubsets.Add(subset);
                return; 
            }            
             
            // depth first search using recusive function 
            for (int i = start; i < numbers.Length; i++)
            {
                var visit   = numbers[i];
                var current = i;

                var newList = new List<int>(subset); 
                newList.Add(visit);
                findSubsetWithSum(allSubsets, newList, numbers, remaining - visit, current);                
            }            
        }
    }
}