x = importdata('input.txt');
L = size(x,1);
g = zeros(L,L);
% not counting = 0, open = 1, trees = 2, lumberyard = 3
for i=1:L
    g(i,x{i,:}=='.') = 1;
    g(i,x{i,:}=='|') = 2;
    g(i,x{i,:}=='#') = 3;
end
g = [zeros(L,1),g,zeros(L,1)];
g = [zeros(1,L+2);g;zeros(1,L+2)];

gNew = g;
N = 1000;
y = zeros(N,1);
for i=1:1000
    for r=2:size(g,1)-1
        for c=2:size(g,2)-1

            switch g(r,c)

                case 1

                    if (g(r-1,c-1)==2) + (g(r-1,c)==2) +(g(r-1,c+1)==2)+(g(r,c-1)==2)+(g(r,c+1)==2) + (g(r+1,c-1)==2) + (g(r+1,c)==2) + (g(r+1,c+1)==2) > 2
                        gNew(r,c) = 2;
                    end

                case 2

                    if (g(r-1,c-1)==3) + (g(r-1,c)==3) +(g(r-1,c+1)==3)+(g(r,c-1)==3)+(g(r,c+1)==3) + (g(r+1,c-1)==3) + (g(r+1,c)==3) + (g(r+1,c+1)==3) > 2
                        gNew(r,c) = 3;
                    end

                case 3

                    if ((g(r-1,c-1)==3) + (g(r-1,c)==3) +(g(r-1,c+1)==3)+(g(r,c-1)==3)+(g(r,c+1)==3) + (g(r+1,c-1)==3) + (g(r+1,c)==3) + (g(r+1,c+1)==3) > 0) && ((g(r-1,c-1)==2) + (g(r-1,c)==2) +(g(r-1,c+1)==2)+(g(r,c-1)==2)+(g(r,c+1)==2) + (g(r+1,c-1)==2) + (g(r+1,c)==2) + (g(r+1,c+1)==2) > 0)
                        gNew(r,c) = 3;
                    else
                        gNew(r,c) = 1;
                    end

            end

        end
    end
    g=gNew;
    y(i,1)=sum(sum(g==2))*sum(sum(g==3));
end
disp(y(10,1)) %Part 1

% Plot first 1000 values of resource value
plot(y,'.')
% Visual inspection of plot to find period:
% Period = 977-949 = 28
% y(977) = 214914
% mod(1000000000-977,28) = 23
% y(977+23) = 228490