day 18 python solution

day18/sample1.in

@@ -0,0 +1,13 @@
+2,2,2
+1,2,2
+3,2,2
+2,1,2
+2,3,2
+2,2,1
+2,2,3
+2,2,4
+2,2,6
+1,2,5
+3,2,5
+2,1,5
+2,3,5

day18/sol.py

@@ -0,0 +1,90 @@
+import numpy
+lava = numpy.zeros((23,23,23), dtype=numpy.int32)
+
+for line in open("input"):
+    x,y,z = map(int, line.strip().split(","))
+    lava[x,y,z] = 1
+
+water = numpy.zeros((23,23,23), dtype=numpy.int32)
+
+area = 0
+N = 23
+for x in range(N):
+    for y in range(N):
+        for z in range(N):
+            if lava[x,y,z]:
+                sides = 0
+                def do(x,y,z):
+                    global sides
+                    if 0 <= x < N and 0 <= y < N and 0 <= z < N:
+                        sides += not lava[x,y,z]
+                    else:
+                        sides += 1
+                do(x-1, y, z)
+                do(x+1, y, z)
+                do(x, y-1, z)
+                do(x, y+1, z)
+                do(x, y, z-1)
+                do(x, y, z+1)
+                area += sides
+            else:
+                if 0 in (x,y,z) or N-1 in (x,y,z):
+                    water[x,y,z] = 1
+print(area)
+
+def move(w, axis, amount):
+    w = numpy.roll(w, amount, axis=axis)
+    all = slice(None,None)
+    index = [all,all,all]
+    if amount > 1:
+        index[axis] = 0
+    else:
+        index[axis] = w.shape[axis] - 1
+    w[tuple(index)] = 0
+    return w
+
+def flood(a):
+    while True:
+        x = move(a, 0, -1)
+        x |= move(a, 0, +1)
+        x |= move(a, 1, -1)
+        x |= move(a, 1, +1)
+        x |= move(a, 2, -1)
+        x |= move(a, 2, +1)
+        x = x & ~lava
+        if (a == x).all():
+            return a
+        a = x
+
+
+print(move(numpy.ones((3,3,3)), 1, 1))
+print(move(numpy.ones((3,3,3)), 0, -1))
+
+water = flood(water)
+print(water)
+
+area = 0
+N = 23
+for x in range(N):
+    for y in range(N):
+        for z in range(N):
+            if lava[x,y,z]:
+                sides = 0
+                def do(x,y,z):
+                    global sides
+                    if 0 <= x < N and 0 <= y < N and 0 <= z < N:
+                        sides += not lava[x,y,z] and water[x,y,z]
+                    else:
+                        sides += 1
+                do(x-1, y, z)
+                do(x+1, y, z)
+                do(x, y-1, z)
+                do(x, y+1, z)
+                do(x, y, z-1)
+                do(x, y, z+1)
+                area += sides
+            else:
+                if 0 in (x,y,z) or N-1 in (x,y,z):
+                    water[x,y,z] = 1
+print(area)
+