Added day 10 for 2024

2024/src/day10.py

@@ -0,0 +1,90 @@
+import sys
+from typing import Optional
+from inputs import load_input
+
+
+def part1() -> int:
+    input_strings = load_input("./input/day10")
+    grid = create_grid(input_strings)
+    return count_routes_from_trailheads(grid)
+
+
+def part2() -> int:
+    input_strings = load_input("./input/day10")
+    grid = create_grid(input_strings)
+    return count_routes_from_trailheads(grid, with_distinct_paths=True)
+
+
+def count_routes_from_trailheads(grid: list[list[int]], with_distinct_paths = False) -> int:
+    answer = 0
+    for y, row in enumerate(grid):
+        for x, tile in enumerate(row):
+            if tile == 0:
+                visited = set()
+                if with_distinct_paths:
+                    visited = None
+                result = count_routes_from_point((y, x), grid, visited)
+                answer += result
+    return answer
+
+
+def count_routes_from_point(
+    position: tuple[int, int], grid: list[list[int]], visited: Optional[set[tuple[int, int]]]
+) -> int:
+
+    y, x = position
+    height = grid[y][x]
+    if height == 9:
+        if visited is not None:
+            if position in visited:
+                return 0
+            visited.add(position)
+            return 1
+        return 1
+
+    neighbors = get_valid_neighbors(position, grid)
+    if len(neighbors) == 0:
+        return 0
+    else:
+        answer = 0
+        for each in neighbors:
+            answer += count_routes_from_point(each, grid, visited)
+        return answer
+
+
+def get_valid_neighbors(
+    position: tuple[int, int], grid: list[list[int]]
+) -> list[tuple[int, int]]:
+    y, x = position
+    expected_height = grid[y][x] + 1
+    neighbors = []
+    if y - 1 >= 0:
+        if grid[y - 1][x] == expected_height:
+            neighbors.append((y - 1, x))
+    if y + 1 < len(grid):
+        if grid[y + 1][x] == expected_height:
+            neighbors.append((y + 1, x))
+    if x - 1 >= 0:
+        if grid[y][x - 1] == expected_height:
+            neighbors.append((y, x - 1))
+    if x + 1 < len(grid[y]):
+        if grid[y][x + 1] == expected_height:
+            neighbors.append((y, x + 1))
+    return neighbors
+
+
+def create_grid(input_strings: list[str]) -> list[list[int]]:
+    grid = []
+    for input_string in input_strings:
+        row = []
+        for tile in input_string.strip():
+            if tile == ".":
+                row.append(-1)
+            else:
+                row.append(int(tile))
+        grid.append(row)
+    return grid
+
+
+if __name__ == "__main__":
+    print(globals()[sys.argv[1]]())