2023.09

challenges/2023/09-mirageMaintenance/README.md

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+# [Day 9: Mirage Maintenance](https://adventofcode.com/2023/day/9)

challenges/2023/09-mirageMaintenance/main.py

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+import sys
+from functools import reduce
+from typing import Callable
+
+
+def parse(instr: str) -> list[list[int]]:
+    return [[int(x) for x in line.split(" ")] for line in instr.splitlines()]
+
+
+def get_term(start: list[int], reduction_fn: Callable[[int, list[int]], int]) -> int:
+    seqs = [start]
+    while not reduce(lambda acc, v: acc and v == 0, seqs[-1], True):
+        cs = seqs[-1]
+        x = []
+        for i in range(len(cs) - 1):
+            x.append(cs[i+1] - cs[i])
+        seqs.append(x)
+    return reduce(reduction_fn, seqs[-2::-1], 0)
+
+
+def run(instr: str, reduction_fn: Callable[[int, list[int]], int]):
+    sequences = parse(instr)
+    acc = 0
+    for sq in sequences:
+        acc += get_term(sq, reduction_fn)
+    return acc 
+
+
+def one(instr: str):
+    return run(instr, lambda acc, x: acc + x[-1])
+
+
+def two(instr: str):
+    return run(instr, lambda acc, x: x[0] - acc)
+
+
+def _debug(*args, **kwargs):
+    kwargs["file"] = sys.stderr
+    print(*args, **kwargs)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) < 2 or sys.argv[1] not in ["1", "2"]:
+        print("Missing day argument", file=sys.stderr)
+        sys.exit(1)
+    inp = sys.stdin.read().strip()
+    if sys.argv[1] == "1":
+        print(one(inp))
+    else:
+        print(two(inp))

challenges/2023/09-mirageMaintenance/tests.json

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+{
+    "1": [
+        {"is": "114", "input": "0 3 6 9 12 15\n1 3 6 10 15 21\n10 13 16 21 30 45\n"},
+        {"is": "36", "input": "30 26 24 24 26 30"}
+    ],
+    "2": [
+        {"is": "2", "input": "0 3 6 9 12 15\n1 3 6 10 15 21\n10 13 16 21 30 45\n"},
+        {"is": "36", "input": "30 26 24 24 26 30"}
+    ]
+}

challenges/2023/README.md

@@ -18,3 +18,4 @@ Solutions to the [2023 Advent of Code](https://adventofcode.com/2023).
 | 06 - Wait For It | ★ ★ | Python | Easy, GCSE-level maths :) |
 | 07 - Camel Cards | ★ ★ | Python | Pedantic problem statements will be my downfall |
 | 08 - Haunted Wasteland | ★ ★ | Python | I'm not sure any feasible generic solution exists - but I did work out the infeasible one! |
+| 09 - Mirage Maintenance | ★ ★ | Python | GCSE maths and the n-th term coming in clutch right here |