2021 Day 04

2021/04/code.py

@@ -0,0 +1,90 @@
+# SPDX-License-Identifier: MIT
+# Copyright (c) 2021 Akumatic
+#
+# https://adventofcode.com/2021/day/04
+
+class Draws:
+    def __init__(self, numbers: list):
+        self.draws = numbers[:]
+        self.last_idx = -1
+        self.draws_left = self.last_idx < len(numbers)
+
+    def draw(self) -> int:
+        if not self.draws_left:
+            return None
+        self.last_idx += 1
+        self.draws_left = self.last_idx < len(self.draws)
+        return self.draws[self.last_idx]
+
+class Bingo:
+    def __init__(self, numbers: list):
+        self.field = numbers[:]
+        self.drawn = [False] * 25
+        self.last_number = None
+        self.winner = False
+
+    def draw(self, number: int):
+        if number in self.field:
+            self.last_number = number
+            idx = self.field.index(number)
+            self.drawn[idx] = True
+            self.check_for_win()
+
+    def check_for_win(self) -> bool:
+        for i in range(0, 5):
+            if all(self.drawn[i*5 + j] for j in range(5)) or all(self.drawn[j*5 + i] for j in range(5)):
+                self.winner = True
+                return True
+        return False
+
+    def calculate_score(self):
+        return sum(self.field[i] for i in range(25) if not self.drawn[i]) * self.last_number
+
+def read_file(filename: str = "input.txt") -> list:
+    with open(f"{__file__.rstrip('code.py')}{filename}", "r") as f:
+        lines = [line for line in f.read().split("\n")]
+
+    draws = Draws([int(x) for x in lines[0].split(",")])
+
+    fields = list()
+    cur_nums = list()
+    for i in range(2, len(lines), 6):
+        for j in range(5):
+            cur_nums += [int(x) for x in lines[i + j].lstrip().strip().split()]
+        fields.append(Bingo(cur_nums))
+        cur_nums.clear()
+
+    return draws, fields
+
+def part1(draws: Draws, fields: list) -> int:
+    winner = None
+    while draws.draws_left:
+        num = draws.draw()
+        for f in fields:
+            f.draw(num)
+            if f.winner and winner is None:
+                winner = f
+
+        if winner:
+            return winner.calculate_score()
+    return -1
+            
+def part2(draws: Draws, fields: list) -> int:
+    while draws.draws_left:
+        playing_fields = [field for field in fields if not field.winner]
+        if len(playing_fields) == 1:
+            break
+
+        num = draws.draw()
+        for field in playing_fields:
+            field.draw(num)
+
+    last = playing_fields[0]
+    while not last.winner:
+        last.draw(draws.draw())
+    return last.calculate_score()
+                
+if __name__ == "__main__":
+    draws, fields = read_file()
+    print(f"Part 1: {part1(draws, fields)}")
+    print(f"Part 2: {part2(draws, fields)}")