AoC 2020: day12

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

2020-python/solutions/day_12.py

@@ -0,0 +1,116 @@
+"""AOC 2020 Day 12"""
+
+import pathlib
+import time
+
+TEST_INPUT = """F10
+N3
+F7
+R90
+F11"""
+
+LEFT, RIGHT = 'L', 'R'
+FORWARD = 'F'
+NORTH, SOUTH, EAST, WEST = 'N', 'S', 'E', 'W'
+
+def read_input(input_path: str) -> str:
+    """take input file path and return a str with the file's content"""
+    with open(input_path, 'r') as input_file:
+        input_data = input_file.read().strip()
+        return input_data
+
+def extract(input_data: str) -> list:
+    """take input data and return the appropriate data structure"""
+    entries = []
+    for line in input_data.split('\n'):
+        instruction = (line[0], int(line[1:]))
+        entries.append(instruction)
+    return entries
+
+def rotate_ship(direction: str, rotation: str) -> str:
+    """rotate the ship"""
+    if direction == NORTH:
+        return WEST if rotation == LEFT else EAST
+    if direction == SOUTH:
+        return EAST if rotation == LEFT else WEST
+    if direction == EAST:
+        return NORTH if rotation == LEFT else SOUTH
+    if direction == WEST:
+        return SOUTH if rotation == LEFT else NORTH
+    return None
+
+def move(direction: str, x: int, y: int, value: int) -> tuple:
+    """move the ship or the waypoint"""
+    if direction == NORTH:
+        return (x, y+value)
+    if direction == SOUTH:
+        return (x, y-value)
+    if direction == EAST:
+        return (x+value, y)
+    if direction == WEST:
+        return (x-value, y)
+    return None
+
+def rotate_waypoint(direction: str, x: int, y: int, value: int) -> tuple:
+    """rotate waypoint around ship"""
+    if (direction == LEFT and value == 90) or (direction == RIGHT and value == 270):
+        return (-y, x)
+    if ((direction == LEFT and value == 180) or (direction == RIGHT and value == 180)):
+        return (-x, -y)
+    if ((direction == LEFT and value == 270) or (direction == RIGHT and value == 90)):
+        return (y, -x)
+    return None
+
+def part1(entries: list) -> int:
+    """part1 solver"""
+    direction = EAST
+    x_ship, y_ship = 0, 0
+
+    for action, value in entries:
+        if action == FORWARD:
+            x_ship, y_ship = move(direction, x_ship, y_ship, value)
+        elif action in (LEFT, RIGHT):
+            for _ in range(value//90):
+                direction = rotate_ship(direction, action)
+        else:
+            x_ship, y_ship = move(action, x_ship, y_ship, value)
+    return abs(x_ship) + abs(y_ship)
+
+def part2(entries: list) -> int:
+    """part2 solver"""
+    x_ship, y_ship = 0, 0
+    x_wp, y_wp = 10, 1
+
+    for action, value in entries:
+        if action == FORWARD:
+            x_ship += x_wp * value
+            y_ship += y_wp * value
+        elif action in (LEFT, RIGHT):
+            x_wp, y_wp = rotate_waypoint(action, x_wp, y_wp, value)
+        else:
+            x_wp, y_wp = move(action, x_wp, y_wp, value)
+    return abs(x_ship) + abs(y_ship)
+
+def test_input_day_12():
+    """pytest testing function"""
+    entries = extract(TEST_INPUT)
+    assert part1(entries) == 25
+    assert part2(entries) == 286
+
+def test_bench_day_12(benchmark):
+    """pytest-benchmark function"""
+    benchmark(main)
+
+def main():
+    """main function"""
+    input_path = str(pathlib.Path(__file__).resolve().parent.parent) + "/inputs/" + str(pathlib.Path(__file__).stem)
+    start_time = time.time()
+    input_data = read_input(input_path)
+    entries = extract(input_data)
+    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()