2020 Day 03, unified headers for 2020

2020/03/code.py

@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: MIT
+# Copyright (c) 2020 Akumatic
+#
+# https://adventofcode.com/2020/day/3
+
+def readFile() -> list:
+    with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
+        return [line[:-1] for line in f.readlines()]
+
+def count_trees(vals: list, dx: int, dy: int) -> int:
+    x, y, cnt, length, mod = 0, 0, 0, len(vals) - dy, len(vals[0])
+    while y < length:
+        x = (x + dx) % mod
+        y += dy
+        if vals[y][x] == "#":
+            cnt += 1
+    return cnt
+
+def part1(vals: list) -> int:
+    return count_trees(vals, 3, 1)
+
+def part2(vals: list, sol_part1: int) -> int:
+    deltas = ((1, 1), (5, 1), (7, 1), (1, 2))
+    prod = sol_part1
+    for delta in deltas:
+        prod *= count_trees(vals, delta[0], delta[1])
+    return prod
+
+def test():
+    test_input = ["..##.......", "#...#...#..", ".#....#..#.",
+    "..#.#...#.#", ".#...##..#.", "..#.##.....", ".#.#.#....#",
+    ".#........#", "#.##...#...", "#...##....#", ".#..#...#.#"]
+    assert part1(test_input) == 7
+    assert part2(test_input, 7) == 336
+
+if __name__ == "__main__":
+    test()
+    vals = readFile()
+    sol_part1 = part1(vals)
+    print(f"Part 1: {sol_part1}")
+    print(f"Part 2: {part2(vals, sol_part1)}")