Solve day 15 (part 2 bruteforce)

2020/day15_memory.py

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+import functools
+import re
+from typing import Dict, Iterable, List, Tuple, Union
+
+
+def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
+    print(f"\n+ Running on {filename}")
+    with open(filename) as f:
+        starting_numbers = list(map(int, f.read().strip().split("\n")[0].split(",")))
+
+    counter_part_1 = solve_part_1(starting_numbers)
+
+    print(f"1. Found {counter_part_1}")
+    if expected_part_1:
+        assert expected_part_1 == counter_part_1
+
+    counter_part_2 = solve_part_2(starting_numbers)
+    print(f"2. Found {counter_part_2}")
+    if expected_part_2:
+        assert expected_part_2 == counter_part_2
+
+
+SeenTuple = Union[Tuple[int], Tuple[int, int]]
+Seen = Dict[int, SeenTuple]
+
+
+def solve_part_1(starting_numbers):
+    return solve(starting_numbers, 2020)
+
+
+def solve(starting_numbers, limit):
+    seen = dict()  # type: Seen
+    previous = 0
+    for turn, current in enumerate(starting_numbers):
+        seen[current] = (turn,)
+        previous = current
+    previous_first_time = True
+    for turn in range(len(starting_numbers), limit):
+        if previous_first_time:
+            current = 0
+        else:
+            current = seen[previous][0] - seen[previous][1]
+        seen[current] = seen_tuple(seen, current, turn)
+        previous = current
+        previous_first_time = first_time_seen(seen, previous)
+    return previous
+
+
+def first_time_seen(seen: Seen, previous: int) -> bool:
+    return len(seen[previous]) == 1
+
+
+def seen_tuple(seen: Seen, current: int, turn: int) -> SeenTuple:
+    try:
+        existing = seen[current]
+        return turn, existing[0]
+    except KeyError:
+        return (turn,)
+
+
+def solve_part_2(starting_numbers):
+    return solve(starting_numbers, 30_000_000)
+
+
+if __name__ == "__main__":
+    main("inputs/day15-test1", 436, 175594)
+    main("inputs/day15-test2", 1, 2578)
+    main("inputs/day15-test6", 438, 18)
+    main("inputs/day15-test7", 1836, 362)
+    main("inputs/day15", 595, 1708310)

2020/inputs/day15

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+1,17,0,10,18,11,6

2020/inputs/day15-test1

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+0,3,6

2020/inputs/day15-test2

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+1,3,2

2020/inputs/day15-test6

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+3,2,1

2020/inputs/day15-test7

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+3,1,2

2020/template.py

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+import functools
+import re
+from typing import Dict, Iterable, List, Union
+
+
+def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
+    print(f"\n+ Running on {filename}")
+    with open(filename) as f:
+        data = f.read().strip().split("\n")
+
+    counter_part_1 = solve_part_1(data)
+
+    print(f"1. Found {counter_part_1}")
+    if expected_part_1:
+        assert expected_part_1 == counter_part_1
+
+    counter_part_2 = solve_part_2(data)
+    print(f"2. Found {counter_part_2}")
+    if expected_part_2:
+        assert expected_part_2 == counter_part_2
+
+
+def solve_part_1(data):
+    return 0
+
+
+def solve_part_2(data):
+    return 0
+
+
+if __name__ == "__main__":
+    main("inputs/day14-test1", 436)
+    main("inputs/day14-test2", 1)
+    main("inputs/day14")