2021 day 6.

2021/day4.py

@@ -13,12 +13,15 @@ boards = np.asarray(
     ]
 )
 
-# part 1
-marked = np.zeros_like(boards, dtype=bool)
+# (round, score) for each board (-1 when not found)
 winning_rounds: list[tuple[int, int]] = [(-1, -1) for _ in range(len(boards))]
+marked = np.zeros_like(boards, dtype=bool)
+
 for round, number in enumerate(numbers):
+    # mark boards
     marked[boards == number] = True
 
+    # check each board for winning
     for index in range(len(boards)):
         if winning_rounds[index][0] > 0:
             continue
@@ -29,9 +32,11 @@ for round, number in enumerate(numbers):
                 number * int(np.sum(boards[index][~marked[index]])),
             )
 
+    # all boards are winning - break
     if np.all(marked.all(axis=1) | marked.all(axis=2)):
         break
 
+# part 1
 (_, score) = min(winning_rounds, key=lambda w: w[0])
 print(f"answer 1 is {score}")
 

2021/day6.py

@@ -1,13 +1,21 @@
 import sys
-from collections import defaultdict
-from dataclasses import dataclass
 
-lines = sys.stdin.read().splitlines()
+values = [int(c) for c in sys.stdin.read().strip().split(",")]
+
+days = 256
+lanterns = {day: 0 for day in range(days)}
+for value in values:
+    for day in range(value, days, 7):
+        lanterns[day] += 1
+
+for day in range(days):
+    for day2 in range(day + 9, days, 7):
+        lanterns[day2] += lanterns[day]
 
 # part 1
-answer_1 = ...
+answer_1 = sum(v for k, v in lanterns.items() if k < 80) + len(values)
 print(f"answer 1 is {answer_1}")
 
 # part 2
-answer_2 = ...
+answer_2 = sum(lanterns.values()) + len(values)
 print(f"answer 2 is {answer_2}")

2021/inputs/day6.txt

@@ -0,0 +1 @@
+2,3,1,3,4,4,1,5,2,3,1,1,4,5,5,3,5,5,4,1,2,1,1,1,1,1,1,4,1,1,1,4,1,3,1,4,1,1,4,1,3,4,5,1,1,5,3,4,3,4,1,5,1,3,1,1,1,3,5,3,2,3,1,5,2,2,1,1,4,1,1,2,2,2,2,3,2,1,2,5,4,1,1,1,5,5,3,1,3,2,2,2,5,1,5,2,4,1,1,3,3,5,2,3,1,2,1,5,1,4,3,5,2,1,5,3,4,4,5,3,1,2,4,3,4,1,3,1,1,2,5,4,3,5,3,2,1,4,1,4,4,2,3,1,1,2,1,1,3,3,3,1,1,2,2,1,1,1,5,1,5,1,4,5,1,5,2,4,3,1,1,3,2,2,1,4,3,1,1,1,3,3,3,4,5,2,3,3,1,3,1,4,1,1,1,2,5,1,4,1,2,4,5,4,1,5,1,5,5,1,5,5,2,5,5,1,4,5,1,1,3,2,5,5,5,4,3,2,5,4,1,1,2,4,4,1,1,1,3,2,1,1,2,1,2,2,3,4,5,4,1,4,5,1,1,5,5,1,4,1,4,4,1,5,3,1,4,3,5,3,1,3,1,4,2,4,5,1,4,1,2,4,1,2,5,1,1,5,1,1,3,1,1,2,3,4,2,4,3,1

2021/tests/day6.txt

@@ -0,0 +1 @@
+3,4,3,1,2