Solution to problem 17 part 2 in Python

src/2020/P17.py

@@ -217,5 +217,311 @@ def part_1() -> None:
     print(f"After 6 cycles in 3D, we have {len(active_points)} active cubes")
 
 
+# --- Part Two ---
+
+# For some reason, your simulated results don't match what the experimental
+# energy source engineers expected. Apparently, the pocket dimension actually
+# has four spatial dimensions, not three.
+
+# The pocket dimension contains an infinite 4-dimensional grid. At every
+# integer 4-dimensional coordinate (x,y,z,w), there exists a single cube
+# (really, a hypercube) which is still either active or inactive.
+
+# Each cube only ever considers its neighbors: any of the 80 other cubes where
+# any of their coordinates differ by at most 1. For example, given the cube at
+# x=1,y=2,z=3,w=4, its neighbors include the cube at x=2,y=2,z=3,w=3, the cube
+# at x=0,y=2,z=3,w=4, and so on.
+
+# The initial state of the pocket dimension still consists of a small flat
+# region of cubes. Furthermore, the same rules for cycle updating still apply:
+# during each cycle, consider the number of active neighbors of each cube.
+
+# For example, consider the same initial state as in the example above. Even
+# though the pocket dimension is 4-dimensional, this initial state represents a
+# small 2-dimensional slice of it. (In particular, this initial state defines a
+# 3x3x1x1 region of the 4-dimensional space.)
+
+# Simulating a few cycles from this initial state produces the following
+# configurations, where the result of each cycle is shown layer-by-layer at
+# each given z and w coordinate:
+
+# Before any cycles:
+
+# z=0, w=0
+# .#.
+# ..#
+# ###
+
+
+# After 1 cycle:
+
+# z=-1, w=-1
+# #..
+# ..#
+# .#.
+
+# z=0, w=-1
+# #..
+# ..#
+# .#.
+
+# z=1, w=-1
+# #..
+# ..#
+# .#.
+
+# z=-1, w=0
+# #..
+# ..#
+# .#.
+
+# z=0, w=0
+# #.#
+# .##
+# .#.
+
+# z=1, w=0
+# #..
+# ..#
+# .#.
+
+# z=-1, w=1
+# #..
+# ..#
+# .#.
+
+# z=0, w=1
+# #..
+# ..#
+# .#.
+
+# z=1, w=1
+# #..
+# ..#
+# .#.
+
+
+# After 2 cycles:
+
+# z=-2, w=-2
+# .....
+# .....
+# ..#..
+# .....
+# .....
+
+# z=-1, w=-2
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=0, w=-2
+# ###..
+# ##.##
+# #...#
+# .#..#
+# .###.
+
+# z=1, w=-2
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=2, w=-2
+# .....
+# .....
+# ..#..
+# .....
+# .....
+
+# z=-2, w=-1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=-1, w=-1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=0, w=-1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=1, w=-1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=2, w=-1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=-2, w=0
+# ###..
+# ##.##
+# #...#
+# .#..#
+# .###.
+
+# z=-1, w=0
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=0, w=0
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=1, w=0
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=2, w=0
+# ###..
+# ##.##
+# #...#
+# .#..#
+# .###.
+
+# z=-2, w=1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=-1, w=1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=0, w=1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=1, w=1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=2, w=1
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=-2, w=2
+# .....
+# .....
+# ..#..
+# .....
+# .....
+
+# z=-1, w=2
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=0, w=2
+# ###..
+# ##.##
+# #...#
+# .#..#
+# .###.
+
+# z=1, w=2
+# .....
+# .....
+# .....
+# .....
+# .....
+
+# z=2, w=2
+# .....
+# .....
+# ..#..
+# .....
+# .....
+
+# After the full six-cycle boot process completes, 848 cubes are left in the
+# active state.
+
+# Starting with your given initial configuration, simulate six cycles in a
+# 4-dimensional space. How many cubes are left in the active state after the
+# sixth cycle?
+
+
+def part_2() -> None:
+    active_points = get_active_points(dim=4)
+    for it in range(6):
+        new_active_points = set()
+        # check x,y,z point
+        for x in range(-10 - it, it + 10):
+            for y in range(-10 - it, it + 10):
+                for z in range(-2 - it, it + 2):
+                    for w in range(-2 - it, it + 2):
+                        point = (x, y, z, w)
+
+                        # for the current point, check the neighbors
+                        num_actives = 0
+                        for delta in iter.product(range(-1, 2), repeat=4):
+                            if delta != (0,) * 4:
+                                if (
+                                    tuple(
+                                        [a + b for a, b in zip(point, delta)]
+                                    )
+                                    in active_points
+                                ):
+                                    num_actives += 1
+
+                        # apply rules
+                        if point in active_points and (
+                            num_actives == 2 or num_actives == 3
+                        ):
+                            new_active_points.add(point)
+                        if point not in active_points and num_actives == 3:
+                            new_active_points.add(point)
+
+        # next iteration
+        active_points = new_active_points
+    print(f"After 6 cycles in 4D, we have {len(active_points)} active cubes")
+
+
 if __name__ == "__main__":
     part_1()
+    part_2()