18

1 files changed, 45 insertions, 0 deletions

diff --git a/18.py b/18.py
new file mode 100644
index 0000000..047a942
--- /dev/null
+++ b/18.py
@@ -0,0 +1,45 @@
+from utils import open_day
+
+with open_day(18) as f:
+    points = {tuple(map(int, line.rstrip().split(','))) for line in f}
+
+def neighbours(p):
+    yield (p[0] + 1, p[1]    , p[2]    )
+    yield (p[0] - 1, p[1]    , p[2]    )
+    yield (p[0]    , p[1] + 1, p[2]    )
+    yield (p[0]    , p[1] - 1, p[2]    )
+    yield (p[0]    , p[1]    , p[2] + 1)
+    yield (p[0]    , p[1]    , p[2] - 1)
+
+p1 = 0
+for point in points:
+    for n in neighbours(point):
+        if n not in points:
+            p1 += 1
+print(p1)
+
+it = iter(points)
+minx, miny, minz = next(it)
+maxx, maxy, maxz = minx, miny, minz
+for x, y, z in it:
+    if x < minx: minx = x
+    elif x > maxx: maxx = x
+    if y < miny: miny = y
+    elif y > maxy: maxy = y
+    if z < minz: minz = z
+    elif z > maxz: maxz = z
+
+p2 = 0
+to_visit = {(minx - 1, miny - 1, minz - 1)}
+visited = set()
+while to_visit:
+    p = to_visit.pop()
+    visited.add(p)
+    for n in neighbours(p):
+        if not (minx - 1 <= n[0] <= maxx + 1): continue
+        if not (miny - 1 <= n[1] <= maxy + 1): continue
+        if not (minz - 1 <= n[2] <= maxz + 1): continue
+        if n in visited: continue
+        if n in points: p2 += 1
+        else: to_visit.add(n)
+print(p2)