day18

day18.py

@@ -0,0 +1,72 @@
+from heapq import heappush, heappop
+from tools.aoc import AOCDay
+from tools.coordinate import Coordinate, DistanceAlgorithm
+from tools.grid import Grid
+from typing import Any
+
+
+def get_path(memory: Grid) -> set[Coordinate]:
+    queue = [(0, 0, Coordinate(0, 0), set())]
+    target = Coordinate(memory.maxX, memory.maxY)
+    visited = set()
+    while queue:
+        _, cost, pos, path = heappop(queue)
+        if pos == target:
+            return path
+        if pos in visited:
+            continue
+        visited.add(pos)
+
+        for n in memory.getNeighboursOf(pos, includeDiagonal=False, includeDefault=True):
+            if memory.get(n):
+                continue
+
+            target_dist = n.getDistanceTo(target, algorithm=DistanceAlgorithm.MANHATTAN, includeDiagonals=False)
+            heappush(queue, (cost + target_dist, cost + 1, n, path | {n}))
+
+    return set()
+
+
+class Day(AOCDay):
+    inputs = [
+        [
+            (22, "input18_test"),
+            (248, "input18"),
+        ],
+        [
+            ("6,1", "input18_test"),
+            ("32,55", "input18"),
+        ],
+    ]
+
+    def parse_input(self) -> tuple[int, Grid, list[Coordinate]]:
+        memory = Grid()
+        memory.maxX = 70 if not self.is_test() else 6
+        memory.maxY = 70 if not self.is_test() else 6
+        falling_bytes = [Coordinate(x, y) for x, y in self.getIntsFromInput()]
+        steps = 1024 if not self.is_test() else 12
+        for i in range(steps):
+            memory.set(falling_bytes[i])
+
+        return steps, memory, falling_bytes
+
+    def part1(self) -> Any:
+        _, memory, falling_bytes = self.parse_input()
+        return len(get_path(memory))
+
+    def part2(self) -> Any:
+        steps, memory, falling_bytes = self.parse_input()
+
+        path = get_path(memory)
+        for i in range(steps + 1, len(falling_bytes)):
+            memory.set(falling_bytes[i])
+            if falling_bytes[i] not in path:
+                continue
+            path = get_path(memory)
+            if not path:
+                return str(falling_bytes[i])[1:-1]
+
+
+if __name__ == "__main__":
+    day = Day(2024, 18)
+    day.run(verbose=True)

inputs/input18_test

@@ -0,0 +1,25 @@
+5,4
+4,2
+4,5
+3,0
+2,1
+6,3
+2,4
+1,5
+0,6
+3,3
+2,6
+5,1
+1,2
+5,5
+2,5
+6,5
+1,4
+0,4
+6,4
+1,1
+6,1
+1,0
+0,5
+1,6
+2,0