➗

VERSION

@@ -1 +1 @@
-💧
+➗

y2023/p18.py

@@ -1,58 +1,72 @@
-def render(graph):
+def render(graph, default='.'):
     xmin, *_, xmax = sorted(int(p.real) for p in walls)
     ymin, *_, ymax = sorted(int(p.imag) for p in walls)
+    out = ''
     for y in range(ymin, ymax + 1):
         for x in range(xmin, xmax + 1):
-            print('#' if complex(x, y) in graph else '.', end='')
-        print()
+            out += graph.get(complex(x, y), default)
+        out += '\n'
+    return out
+
+
+def connected_components(graph):
+    groups = []
+    while graph:
+        seen = set()
+        edge = {graph.pop()}
+        while edge:
+            seen |= edge
+            edge = {pp + ss for pp in edge for ss in [1, -1, 1j, -1j]} & graph - seen
+        groups.append(seen)
+        graph -= seen
+    return groups
 
 
 text = open(0).read()
+p2 = True
 
 walls = {0}
 pos = 0
 for line in text.splitlines():
     d, n, rest = line.split()
-    n, d = int(rest[1:-1][1:][:5], 16), 'RDLU'[int(rest[-2])]
+    if p2:
+        n, d = int(rest[1:-1][1:][:5], 16), 'RDLU'[int(rest[-2])]
     pos += {'R': 1, 'D': 1j, 'L': -1, 'U': -1j}[d] * int(n)
     walls.add(pos)
 
-smallx = {v: i * 2 for i, v in enumerate(sorted({p.real for p in walls}))}
-smally = {v: i * 2 for i, v in enumerate(sorted({p.imag for p in walls}))}
-walls = {complex(smallx[p.real], smally[p.imag]) for p in walls}
-
+b2s = {
+    complex(bx, by) + dx + dy: 3 * complex(sx, sy) + dx + dy
+    for sx, bx in enumerate(sorted({p.real for p in walls}))
+    for sy, by in enumerate(sorted({p.imag for p in walls}))
+    for dx in [-1, 0, 1] for dy in [-1j, 0, 1j]
+}
 
-walls = {0}
-pos = 0
-smallpos = 0
+pos, smallpos = next(iter(b2s.items()))
+walls = {smallpos}
 for line in text.splitlines():
     d, n, rest = line.split()
-    n, d = int(rest[1:-1][1:][:5], 16), 'RDLU'[int(rest[-2])]
-    pos += {'R': 1, 'D': 1j, 'L': -1, 'U': -1j}[d] * int(n)
-    goal = complex(smallx[pos.real], smally[pos.imag])
-    dirx = (goal - smallpos).real or (goal - smallpos).imag
+    if p2:
+        n, d = int(rest[1:-1][1:][:5], 16), 'RDLU'[int(rest[-2])]
+    dirx = {'R': 1, 'D': 1j, 'L': -1, 'U': -1j}[d]
+    pos += dirx * int(n)
+    goal = b2s[pos]
     while smallpos != goal:
         smallpos += dirx
         walls.add(smallpos)
 
-
-render(walls)
-exit()
-
-
-xmin, *_, xmax = sorted(int(p.real) for p in walls)
-ymin, *_, ymax = sorted(int(p.imag) for p in walls)
+xmin, *_, xmax = sorted(int(p.real) for p in b2s.values())
+ymin, *_, ymax = sorted(int(p.imag) for p in b2s.values())
 void = {complex(x, y) for x in range(xmin, xmax + 1) for y in range(ymin, ymax + 1)} - walls
+groups = connected_components(void)
+inside = {p for g in groups if not any(p.real in {xmin, xmax} or p.imag in {ymin, ymax} for p in g) for p in g}
+solid = inside | walls
 
-groups = []
-while void:
-    seen = set()
-    edge = {void.pop()}
-    while edge:
-        seen |= edge
-        edge = {pp + ss for pp in edge for ss in [1, -1, 1j, -1j]} & void - seen
-    groups.append(seen)
-    void -= seen
+# print(render({k: '#' for k in solid}))
 
-inside = {p for g in groups if not any(p.real in {xmin, xmax} or p.imag in {ymin, ymax} for p in g) for p in g}
-print(len(inside | walls))
+s2b = {v: k for k, v in b2s.items()}
+out = 0
+for smallpos in solid:
+    c1, c2 = s2b[smallpos], s2b[smallpos + 1 + 1j]
+    w, h = (c2 - c1).real, (c2 - c1).imag
+    out += int(w * h)
+print(out)