1 files changed, 25 insertions, 0 deletions
diff --git a/day22.jl b/day22.jl
new file mode 100644
index 0000000..6e13236
--- /dev/null
+++ b/day22.jl
@@ -0,0 +1,25 @@
+grid = Int.(hcat(collect.(readlines("day22.txt"))...).=='#')'
+testgrid = [0 0 1; 1 0 0; 0 0 0]
+
+rule1 = reshape([0 -1 1 0 0 1 -1 0], 2, 2, :)
+rule2 = reshape([0 -1 1 0 1 0 0 1 0 1 -1 0 -1 0 0 -1], 2, 2, :)
+
+function virus(grid, steps, dirs)
+    (i, j), n = div.(size(grid).+1, 2), size(dirs, 3)
+    di, dj, inf = -1, 0, 0
+    g = Dict((i,j)=>grid[i,j]*div(n,2) for i=1:size(grid,1), j=1:size(grid,2))
+    for _=1:steps
+        x = get(g, (i,j), 0)
+        g[i,j] = mod(x+1, n)
+        (di, dj) = [di dj] * dirs[:,:,x+1]
+        if x+1==n/2; inf+=1 end
+        i+=di; j+=dj
+    end
+    inf
+end
+
+part1 = virus(grid, 10^4, rule1)
+part2 = virus(grid, 10^7, rule2)
+
+println(part1)
+println(part2)