Find the count of subsets with given difference, C#

Find the count of subsets with given difference

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            int[] arr = new int[] { 1, 1, 2, 3};
            int diff = 1;
            
            //Formula or trick to find the count of subsets with given difference
            // s1 - s2 = diff
            // s1 - (sum - s1) = diff
            // s1 - sum + s1 = diff
            // 2s1 - sum = diff
            // 2s1 = diff + sum
            // s1 = (diff + sum) / 2;
            int s1 = (diff + arr.Sum()) / 2;
            Console.WriteLine(CountSubsetSum (arr, s1) + " subsets found with given difference " + diff);
        }
        
        private static int CountSubsetSum (int[] arr, int sum)
        {
            int[,] t = new int[arr.Length+1, sum+1];
            
            for (int i=0; i < t.GetLength(0); i++)
            {
                for (int j=0; j < t.GetLength(1); j++)
                {
                    if (j == 0)
                    {
                        t[i, j] = 1;
                        continue;
                    }
                    
                    if (i == 0)
                    {
                        t[i, j] = 0;
                        continue;
                    }
                    
                    if (arr[i-1] <= j)
                    {
                        t[i, j] = t[i-1, j - arr[i-1]] + t[i-1, j];
                    }
                    else
                    {
                        t[i, j] = t[i-1, j];
                    }
                }
            }
            
            return t[arr.Length, sum];
        }
    }
}


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