AoC 2020: day11

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

2020-python/solutions/day_11.py

@@ -0,0 +1,143 @@
+"""AOC 2020 Day 11"""
+
+import pathlib
+import time
+import copy
+
+TEST_INPUT = """L.LL.LL.LL
+LLLLLLL.LL
+L.L.L..L..
+LLLL.LL.LL
+L.LL.LL.LL
+L.LLLLL.LL
+..L.L.....
+LLLLLLLLLL
+L.LLLLLL.L
+L.LLLLL.LL"""
+
+FLOOR = 0
+EMPTY_SEAT = 1
+OCCUPIED_SEAT = 2
+
+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 row in input_data.split('\n'):
+        entries.append([])
+        for seat in row:
+            if seat == '.':
+                entries[-1].append(FLOOR)
+            elif seat == 'L':
+                entries[-1].append(EMPTY_SEAT)
+            elif seat == '#':
+                entries[-1].append(OCCUPIED_SEAT)
+            else:
+                raise ValueError("Invalid seat %s" % seat)
+    return entries
+
+def occupied_adjacent_neighbors(seats: list, row: int, column: int) -> int:
+    """return number of occupied adjacent neighbors of a given seat"""
+    neigh_seats = [(0, -1), (1, -1), (1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1)]
+    neighbors = 0
+    rows = len(seats)
+    columns = len(seats[0])
+    for dy, dx in neigh_seats:
+        nrow, ncolumn = row+dy, column+dx
+        if 0 <= nrow < rows and 0 <= ncolumn < columns and seats[nrow][ncolumn] == OCCUPIED_SEAT:
+            neighbors += 1
+    return neighbors
+
+def occupied_insight_neighbors(seats: list, row: int, column: int) -> int:
+    """return number of occupied in-sight neighbors of a given seat"""
+    neigh_seats = [(0, -1), (1, -1), (1, 0), (1, 1), (0, 1), (-1, 1), (-1, 0), (-1, -1)]
+    neighbors = 0
+    rows = len(seats)
+    columns = len(seats[0])
+    for dy, dx in neigh_seats:
+        nrow, ncolumn = row+dy, column+dx
+        while 0 <= nrow < rows and 0 <= ncolumn < columns:
+            seat = seats[nrow][ncolumn]
+            if seat == OCCUPIED_SEAT:
+                neighbors += 1
+                break
+            elif seat == EMPTY_SEAT:
+                break
+            nrow += dy
+            ncolumn += dx
+    return neighbors
+
+def part1(entries: list) -> int:
+    """part1 solver"""
+    seats = copy.deepcopy(entries)
+    while True:
+        new_grid = []
+        changed = False
+        for y, row in enumerate(seats):
+            new_grid.append([])
+            for x, seat in enumerate(row):
+                neighbors = occupied_adjacent_neighbors(seats, y, x)
+                if seat == EMPTY_SEAT and neighbors == 0:
+                    new_grid[-1].append(OCCUPIED_SEAT)
+                    changed = True
+                elif seat == OCCUPIED_SEAT and neighbors >= 4:
+                    new_grid[-1].append(EMPTY_SEAT)
+                    changed = True
+                else:
+                    new_grid[-1].append(seat)
+        if changed:
+            seats = new_grid
+        else:
+            return sum(row.count(OCCUPIED_SEAT) for row in seats)
+
+def part2(entries: list) -> int:
+    """part2 solver"""
+    seats = copy.deepcopy(entries)
+    while True:
+        new_grid = []
+        changed = False
+        for y, row in enumerate(seats):
+            new_grid.append([])
+            for x, seat in enumerate(row):
+                neighbors = occupied_insight_neighbors(seats, y, x)
+                if seat == EMPTY_SEAT and neighbors == 0:
+                    new_grid[-1].append(OCCUPIED_SEAT)
+                    changed = True
+                elif seat == OCCUPIED_SEAT and neighbors >= 5:
+                    new_grid[-1].append(EMPTY_SEAT)
+                    changed = True
+                else:
+                    new_grid[-1].append(seat)
+        if changed:
+            seats = new_grid
+        else:
+            return sum(row.count(OCCUPIED_SEAT) for row in seats)
+
+def test_input_day_11():
+    """pytest testing function"""
+    entries = extract(TEST_INPUT)
+    assert part1(entries) == 37
+    assert part2(entries) == 26
+
+def test_bench_day_11(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()