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authorj-james2021-05-30 23:16:28 +0000
committerj-james2021-05-30 23:18:20 +0000
commited141d648a66d2ee4056632b7e690bb6c78b50e6 (patch)
treed9401d4b69525d90da425c3762f912ac5ebdc212
parentb4dcb59a8ace92d2a4343ad41a9230b727b1b850 (diff)
Day Seventeen, Part I
-rw-r--r--2020/input/seventeen.txt8
-rw-r--r--2020/seventeen.nim70
2 files changed, 78 insertions, 0 deletions
diff --git a/2020/input/seventeen.txt b/2020/input/seventeen.txt
new file mode 100644
index 0000000..9511cae
--- /dev/null
+++ b/2020/input/seventeen.txt
@@ -0,0 +1,8 @@
+....###.
+#...####
+##.#.###
+..#.#...
+##.#.#.#
+#.######
+..#..#.#
+######.#
diff --git a/2020/seventeen.nim b/2020/seventeen.nim
new file mode 100644
index 0000000..70c1cd4
--- /dev/null
+++ b/2020/seventeen.nim
@@ -0,0 +1,70 @@
+# Day Seventeen: Conway Cubes
+import std/os, std/sets, std/enumerate
+
+let input: string = paramStr(1)
+type Coord = tuple[x,y,z: int]
+
+# Coordinate system: 0,0 is at the top left
+var dimension: HashSet[Coord]
+for y, line in enumerate(lines(input)):
+ for x, cube in line:
+ if cube == '#':
+ dimension.incl((x,y,0))
+ # stdout.write(x, ",", y, " ")
+ # stdout.write(cube)
+ # stdout.write('\n')
+# echo(dimension)
+
+## Return a tuple describing a dimension's largest axes
+func maximum(dim: HashSet[Coord]): tuple[x,y,z: int] =
+ result = (0,0,0)
+ for cube in dim:
+ if abs(cube.x) > result.x: result.x = abs(cube.x)
+ if abs(cube.y) > result.y: result.y = abs(cube.y)
+ if abs(cube.z) > result.z: result.z = abs(cube.z)
+
+## Return the number of cubes neighboring an arbitary point in space
+func neighbors(cube: Coord, dim: HashSet[Coord]): int =
+ result = 0
+ for x in -1 .. 1:
+ for y in -1 .. 1:
+ for z in -1 .. 1:
+ if ((cube.x+x, cube.y+y, cube.z+z) in dim) and ((x,y,z) != (0,0,0)):
+ inc(result)
+
+## Run one cycle of a pocket dimension
+func cycle(dim: HashSet[Coord]): HashSet[Coord] =
+ let max = maximum(dim)
+ for x in -max.x-1 .. max.x+1:
+ for y in -max.y-1 .. max.y+1:
+ for z in -max.z-1 .. max.z+1:
+ let coord = (x,y,z)
+ if coord in dim:
+ if coord.neighbors(dim) == 2 or coord.neighbors(dim) == 3:
+ result.incl(coord)
+ if coord notin dim:
+ if coord.neighbors(dim) == 3:
+ result.incl(coord)
+
+func cycle(dim: HashSet[Coord], reps: int): HashSet[Coord] =
+ result = dim
+ for i in 1 .. reps:
+ result = cycle(result)
+
+## Visualize output
+proc echo(dim: HashSet[Coord]) =
+ let max = maximum(dim)
+ for z in -max.z .. max.z:
+ stdout.write("z=", z, '\n')
+ for y in -max.y .. max.y:
+ for x in -max.x .. max.x:
+ if (x,y,z) == (0,0,0):
+ stdout.write('0')
+ elif (x,y,z) in dim:
+ stdout.write('#')
+ else:
+ stdout.write('.')
+ stdout.write('\n')
+ stdout.write('\n')
+
+echo len(dimension.cycle(6))