2020 Day 15

2020/15/code.py

@@ -0,0 +1,36 @@
+# SPDX-License-Identifier: MIT
+# Copyright (c) 2020 Akumatic
+#
+#https://adventofcode.com/2020/day/15
+
+def readFile() -> tuple:
+    with open(f"{__file__.rstrip('code.py')}input.txt", "r") as f:
+        return [int(num) for num in f.readline().split(",")]
+
+def play(input: list, turns: int) -> int:
+    mem = {val: [idx + 1] for idx, val in enumerate(input)}
+    prev = input[-1]
+    for turn in range(len(input) + 1, turns + 1):
+        # set last spoken number
+        if prev not in mem or len(mem[prev]) == 1:
+            prev = 0
+        else: 
+            prev = mem[prev][-1] - mem[prev][-2]
+        # store the counter
+        if prev in mem:
+            mem[prev].append(turn)
+        else:
+            mem[prev] = [turn]
+
+    return prev
+
+def part1(input: list) -> int:
+    return play(input, 2020)
+
+def part2(input: list) -> int:
+    return play(input, 30000000)
+
+if __name__ == "__main__":
+    input = readFile()
+    print(f"Part 1: {part1(input)}")
+    print(f"Part 2: {part2(input)}")