day24.m

tiles = getData('input.txt');
un = unique(tiles);
tiles = un(groupcounts(tiles) ==1);
part1 = length(tiles)

for k = 1:100
    tiles = generation(tiles);
end
part2 = length(tiles)

function nexttiles = generation(tiles)
directions = [2;-2;1-1i;-1-1i;-1+1i;1+1i];
nexttiles = [];
    for i = 1:length(tiles)
        n = 0;
        tile = tiles(i);
        neighbors = tile+directions;
        for j = 1:6
            if ismember(neighbors(j),tiles)
                n = n+1;
            else
                m = 0;
                neighborsneighbors = neighbors(j)+directions;
                for k = 1:6
                    if ismember(neighborsneighbors(k),tiles)
                        m = m+1;
                    end
                end
                if m == 2
                    nexttiles = union(neighbors(j),nexttiles);
                end
            end
        end
        if n > 0 && n <= 2
            nexttiles = union(tile,nexttiles);
        end
    end
end

function data = getData(inputfile)
  inp = string(strsplit(fileread(inputfile),"\n"))';
  inp = strip(inp(1:end-1));
  data = zeros(length(inp),1);
  dirs = ["se","sw","nw","ne","w","e"];
  for i = 1:length(inp)
      for j = 1:length(dirs)
          c = count(inp{i},dirs{j});
          inp{i} = erase(inp{i},dirs{j});
          switch dirs{j}
              case "e"
                  data(i) = data(i) + c*2;
              case "w"
                  data(i) = data(i) - c*2;
              case "se"
                  data(i) = data(i) + c*(1-1i);
              case "sw"
                  data(i) = data(i) + c*(-1-1i);
              case "nw"
                  data(i) = data(i) + c*(-1+1i);
              case "ne"
                  data(i) = data(i) + c*(1+1i);
          end
      end         
  end
end