Poetry stuff.

src/holt59/aoc/2023/day14.py

@@ -0,0 +1,68 @@
+import sys
+from typing import TypeAlias
+
+RockGrid: TypeAlias = list[list[str]]
+
+rocks0 = [list(line) for line in sys.stdin.read().splitlines()]
+
+
+def slide_rocks_top(rocks: RockGrid) -> RockGrid:
+    top = [0 if c == "." else 1 for c in rocks[0]]
+    for row in range(1, len(rocks)):
+        for col in range(len(rocks[0])):
+            match rocks[row][col]:
+                case "O":
+                    if top[col] != row:
+                        rocks[top[col]][col] = "O"
+                        rocks[row][col] = "."
+                    top[col] = top[col] + 1
+                case "#":
+                    top[col] = row + 1
+                case _:
+                    pass
+    return rocks
+
+
+def cycle(rocks: RockGrid) -> RockGrid:
+    for _ in range(4):
+        rocks = slide_rocks_top(rocks)
+        rocks = [
+            [rocks[len(rocks) - j - 1][i] for j in range(len(rocks))]
+            for i in range(len(rocks[0]))
+        ]
+
+    return rocks
+
+
+rocks = slide_rocks_top([[c for c in r] for r in rocks0])
+
+# part 1
+answer_1 = sum(
+    (len(rocks) - i) * sum(1 for c in row if c == "O") for i, row in enumerate(rocks)
+)
+print(f"answer 1 is {answer_1}")
+
+# part 2
+rocks = rocks0
+
+N = 1000000000
+cycles: list[RockGrid] = []
+i_cycle: int = -1
+for i_cycle in range(N):
+    rocks = cycle(rocks)
+
+    if any(rocks == c for c in cycles):
+        break
+
+    cycles.append([[c for c in r] for r in rocks])
+
+cycle_start = next(i for i in range(len(cycles)) if (rocks == cycles[i]))
+cycle_length = i_cycle - cycle_start
+
+ci = cycle_start + (N - cycle_start) % cycle_length - 1
+
+answer_2 = sum(
+    (len(rocks) - i) * sum(1 for c in row if c == "O")
+    for i, row in enumerate(cycles[ci])
+)
+print(f"answer 2 is {answer_2}")