AoC 2020: day4

Signed-off-by: Ettore Dreucci <ettore.dreucci@gmail.com>

2020-python/solutions/day_3.py

@@ -0,0 +1,59 @@
+"""AOC Day 3"""
+
+import pathlib
+import time
+
+def read_input(input_path: str) -> list:
+    """take input file path and return appropriate data structure"""
+    with open(input_path, 'r') as input_file:
+        lines = list()
+        for line in input_file.readlines():
+            lines.append(line.strip())
+        return lines
+
+
+def slope_tree_check(lines: list, dx: int, dy: int) -> int:
+    """check how many trees would be encountered with a specific slope"""
+    x_pos = 0
+    y_pos = 0
+    trees_encountered = 0
+    line_length = len(lines[0])
+    while y_pos < len(lines):
+        if lines[y_pos][x_pos] == '#':
+            trees_encountered += 1
+        x_pos = (x_pos + dx) % line_length
+        y_pos += dy
+    return trees_encountered
+
+def part1(entries: list) -> int:
+    """part1 solver take a list of strings and return an int"""
+    return slope_tree_check(entries, 3, 1)
+
+
+def part2(entries: list) -> int:
+    """part2 solver take a list of tuples and return an int"""
+    slopes = [
+        (1, 1),
+        (3, 1),
+        (5, 1),
+        (7, 1),
+        (1, 2),
+        ]
+    prod = 1
+    for slope in slopes:
+        prod *= slope_tree_check(entries, slope[0], slope[1])
+    return prod
+
+def main():
+    """main function"""
+    input_path = str(pathlib.Path(__file__).resolve().parent.parent) + "/inputs/" + str(pathlib.Path(__file__).stem)
+    entries = read_input(input_path)
+    start_time = time.time()
+    print("Part 1: %d" % part1(entries))
+    print("Part 2: %d" % part2(entries))
+    end_time = time.time()
+    print("Execution time: %f" % (end_time-start_time))
+
+
+if __name__ == "__main__":
+    main()