day 24 hurts my brain, thanks reddit

2024/day22/day22.py

@@ -0,0 +1,58 @@
+from collections import defaultdict
+
+
+def day22(input: str, part: int) -> int:
+    total: int = 0
+
+    last_four_diffs_to_price: dict[tuple[int, int, int, int], int] = defaultdict(int)
+
+    for line in input.splitlines():
+        nums: list[int] = [int(line)]
+        diffs: list[int] = []
+
+        seen_last_fours: set[tuple[int, int, int, int]] = set()
+        for _ in range(2000):
+            nums.append(get_next_secret_number(nums[-1]))
+            diff = nums[-1] % 10 - nums[-2] % 10
+            diffs.append(diff)
+        total += nums[-1]
+
+        for i in range(3, len(diffs)):
+            last_four_diffs = (diffs[i - 3], diffs[i - 2], diffs[i - 1], diffs[i])
+            # only count the first time we've seen this set of diffs, aka only sell once
+            if last_four_diffs in seen_last_fours:
+                continue
+            seen_last_fours.add(last_four_diffs)
+
+            last_four_diffs_to_price[last_four_diffs] += nums[i + 1] % 10
+
+    if part == 1:
+        return total
+
+    most_bananas = max(last_four_diffs_to_price.values())
+    return most_bananas
+
+
+def get_next_secret_number(num: int) -> int:
+    num = (num ^ (num * 64)) % 16777216
+    num = (num ^ (num // 32)) % 16777216
+    num = (num ^ (num * 2048)) % 16777216
+    return num
+
+
+example = """1
+10
+100
+2024"""
+
+input = open("input.txt").read().strip()
+
+print(f"part1 example: {day22(example, 1)} want 37327623")
+print(f"part1 actual: {day22(input, 1)} want 17612566393")
+
+example_part_2 = """1
+2
+3
+2024"""
+print(f"part2 example: {day22(example_part_2, 2)} want 23")
+print(f"part2 actual: {day22(input, 2)} want 1968")