Solve 2024 till day 18

2024/d15.py

@@ -0,0 +1,92 @@
+from lib import get_data
+from lib import Grid2D
+
+DIRS = {
+    "^": (-1, 0),
+    ">": (0, 1),
+    "v": (1, 0),
+    "<": (0, -1),
+}
+
+data = get_data(__file__)
+data, moves = data.split("\n\n")
+
+g = Grid2D(data)
+
+
+def simulate(grid: Grid2D, moves: str):
+    (p,) = g.find("@")
+    for c in moves:
+        if c == "\n":
+            continue
+        d = DIRS[c]
+
+        to_move = set([p])
+        row = to_move
+        blocked = False
+        while True:
+            nrow = set()
+            for (
+                r,
+                c,
+            ) in row:
+                np = r + d[0], c + d[1]
+                if g[np] == "#":
+                    blocked = True
+                elif g[np] == "O":
+                    nrow.add(np)
+                elif g[np] == "[":
+                    nrow.add(np)
+                    if d == (1, 0) or d == (-1, 0):
+                        nrow.add((np[0], np[1] + 1))
+                elif g[np] == "]":
+                    if d == (1, 0) or d == (-1, 0):
+                        nrow.add((np[0], np[1] - 1))
+                    nrow.add(np)
+            to_move |= row
+            row = nrow
+            if len(row) == 0 or blocked:
+                break
+
+        if not blocked:
+            to_place = {}
+            p = p[0] + d[0], p[1] + d[1]
+
+            for tm in to_move:
+                np = tm[0] + d[0], tm[1] + d[1]
+                to_place[np] = g[tm]
+                g[tm] = "."
+
+            for pos, c in to_place.items():
+                g[pos] = c
+
+
+def score(g: Grid2D) -> int:
+    os = g.find("O")
+    if os:
+        return sum(r * 100 + c for r, c in os)
+    return sum(r * 100 + c for r, c in g.find("["))
+
+
+simulate(g, moves)
+print(score(g))
+
+ndata = ""
+for c in data:
+    if c == "#":
+        ndata += "##"
+    elif c == "O":
+        ndata += "[]"
+    elif c == ".":
+        ndata += ".."
+    elif c == "@":
+        ndata += "@."
+    else:
+        ndata += c
+
+g = Grid2D(ndata)
+(p,) = g.find("@")
+
+simulate(g, moves)
+print(score(g))
+exit()