1 files changed, 83 insertions, 0 deletions
diff --git a/2024/15/python.py b/2024/15/python.py
new file mode 100755
index 0000000..4cfd48c
--- /dev/null
+++ b/2024/15/python.py
@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+
+from fileinput import input
+from itertools import takewhile
+
+inp = map(str.strip, input())
+
+grid = {
+    complex(x, y): c
+    for y, line in enumerate(takewhile(bool, inp))
+    for x, c in enumerate(line)
+}
+grid_gold = {}
+for p, c in grid.items():
+    p += p.real
+    match c:
+        case "#" | ".":
+            grid_gold[p] = grid_gold[p + 1] = c
+        case "O":
+            grid_gold[p] = "["
+            grid_gold[p + 1] = "]"
+        case "@":
+            grid_gold[p] = "@"
+            grid_gold[p + 1] = "."
+
+
+moves = "".join(inp)
+
+bot = next(p for p, c in grid.items() if c == "@")
+bot_gold = bot + bot.real
+
+
+def debug(grid):
+    xmax, ymax = (max(p.real for p in grid.keys()), max(p.imag for p in grid.keys()))
+    for y in range(int(ymax) + 1):
+        for x in range(int(xmax) + 1):
+            print(grid[complex(x, y)], end="")
+        print()
+    print()
+
+
+def push(grid, x, v, modify=True):
+    match grid[x], v:
+        case ".", _:
+            return True
+        case "#", _:
+            return False
+        case "[", (1j | -1j) if push(grid, x + v, v, modify) and push(
+            grid, x + v + 1, v, modify
+        ):
+            if modify:
+                grid[x + v] = grid[x]
+                grid[x + v + 1] = grid[x + 1]
+                grid[x] = "."
+                grid[x + 1] = "."
+            return True
+        case "[", (1j | -1j):
+            return False
+        # Push other one
+        case "]", (1j | -1j):
+            return push(grid, x - 1, v, modify)
+        case _, _ if push(grid, x + v, v, modify):
+            if modify:
+                grid[x + v] = grid[x]
+            return True
+
+
+dirs = {">": 1, "v": 1j, "<": -1, "^": -1j}
+for m in map(dirs.get, moves):
+    if push(grid, bot, m):
+        grid[bot] = "."
+        bot += m
+    if push(grid_gold, bot_gold, m, modify=False):
+        push(grid_gold, bot_gold, m, modify=True)
+        grid_gold[bot_gold] = "."
+        bot_gold += m
+
+
+silver = int(sum(p.real + 100 * p.imag for p, c in grid.items() if c == "O"))
+gold = int(sum(p.real + 100 * p.imag for p, c in grid_gold.items() if c == "["))
+
+print("silver:", silver)
+print("gold:", gold)