day18 - just count the surface, don't bother with internals

day18.py

@@ -5,46 +5,6 @@ from tools.grid import Grid
 from typing import Any
 
 
-def get_pocket_region(grid: Grid, start: Coordinate, ignore: set) -> set:
-    if grid.get(start):
-        return set()
-    q = deque()
-    q.append(start)
-    p = {start}
-    border_reached = False
-    while q:
-        c = q.pop()
-        if c in ignore or grid.get(c):
-            continue
-        ignore.add(c)
-        n = list(grid.getNeighboursOf(c, includeDefault=True, includeDiagonal=False))
-        if len(n) < 6:
-            border_reached = True
-            p = set()
-        for nc in n:
-            if grid.get(nc):
-                continue
-            q.append(nc)
-            if not border_reached:
-                p.add(nc)
-
-    return p
-
-
-def get_pocket_cells(grid: Grid) -> set:
-    p = set()
-    v = set()
-    for x in grid.rangeX():
-        for y in grid.rangeY():
-            for z in grid.rangeZ():
-                c = Coordinate(x, y, z)
-                if c in v:
-                    continue
-                p |= get_pocket_region(grid, c, v)
-
-    return p
-
-
 class Day(AOCDay):
     inputs = [
         [
@@ -64,6 +24,8 @@ class Day(AOCDay):
         for line in self.getInput():
             grid.set(Coordinate(*map(int, line.split(","))))
 
+        grid.minX, grid.maxX, grid.minY, grid.maxY, grid.minZ, grid.maxZ = \
+            grid.minX - 1, grid.maxX + 1, grid.minY - 1, grid.maxY + 1, grid.minZ - 1, grid.maxZ + 1
         return grid
 
     def part1(self) -> Any:
@@ -77,12 +39,19 @@ class Day(AOCDay):
     def part2(self) -> Any:
         grid = self.get_grid()
         side_count = 0
-        p = get_pocket_cells(grid)
+        q = deque()
-        for c in grid.getActiveCells():
+        q.append(Coordinate(grid.minX, grid.minY, grid.minZ))
-            side_count += 6
+        v = set()
-            for n in list(grid.getNeighboursOf(c, includeDiagonal=False, includeDefault=True)):
+        while q:
-                if grid.get(n) or n in p:
+            c = q.pop()
-                    side_count -= 1
+            if c in v:
+                continue
+            v.add(c)
+            for n in grid.getNeighboursOf(c, includeDiagonal=False, includeDefault=True):
+                if grid.get(n):
+                    side_count += 1
+                else:
+                    q.append(n)
 
         return side_count