component labeling

ComponentLabeling.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace connected
{

    class Program
    {
        static (int groupNum, char value) nullGroupVal = (-1, '*');
        static char[,] data = 
        {
            { ' ',' ','#','#',' ',' ' },
            { ' ','#','#','#','#',' ' },
            { ' ',' ',' ',' ',' ',' ' },
            { ' ',' ',' ',' ',' ',' ' },
            { 'x',' ','h','h',' ',' ' },
            { 'x',' ','h','h',' ','b' },
        };
        static void Main(string[] args)
        {   
            int groupNum = -1;
            var pixelDC = new Dictionary<(int row, int col), (int groupNum, char value)>();
            for (int row = 0; row < data.GetLength(0); row++)
            {
                for (int col = 0; col < data.GetLength(1); col++)
                {
                    var value = data[row, col];
                    var leftNbor = pixelDC.ContainsKey((row, col-1))? pixelDC[(row, col-1)] : nullGroupVal;
                    var topNbor =  pixelDC.ContainsKey((row-1, col))? pixelDC[(row-1, col)] : nullGroupVal;

                    if(value == leftNbor.value)
                    {
                        pixelDC[(row, col)] = (leftNbor.groupNum, value);
                    }else if(value == topNbor.value && value != leftNbor.value)
                    {
                        pixelDC[(row, col)] = (topNbor.groupNum, value);
                    }
                    
                    if(value == leftNbor.value && value == topNbor.value)
                    {//if conflict
                        var duplicateGroup = topNbor.groupNum;
                        var pixelList = pixelDC.ToList();
                        pixelList = pixelList
                            .Where(px => px.Value.groupNum == duplicateGroup)
                            .ToList();
                        
                        foreach (var px in pixelList)
                        {
                            pixelDC[px.Key] = (leftNbor.groupNum, px.Value.value);
                        }
                    }
                    
                    if(value != leftNbor.value && value != topNbor.value)
                    {   
                        groupNum++;
                        pixelDC[(row, col)] = (groupNum, value);
                    }
                }    
            }

            var finalList = pixelDC.ToList();
            var groups = finalList
                .GroupBy(x => x.Value.groupNum);
            foreach (var group in groups)
            {
                Console.WriteLine(group.Key + "-------------------");
                Console.WriteLine(group.ToList().Select(x => x.Value.value).ToArray());
            }
        }
    }
}