2017: d06: ex2: add solution

2017/d06/ex2/ex2.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python
+
+import itertools
+import sys
+
+MemoryBlocks = tuple[int, ...]
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> MemoryBlocks:
+        return tuple(int(n) for n in input.split())
+
+    def redistribute(nums: MemoryBlocks) -> MemoryBlocks:
+        res = list(nums)
+        i = res.index(max(res))  # Quick and hasty `argmax`
+        n, res[i] = res[i], 0
+        common, remain = n // len(res), n % len(res)
+        for j in range(i + 1, i + remain + 1):
+            res[j % len(res)] += 1
+        for j in range(len(res)):
+            res[j] += common
+        return tuple(res)
+
+    blocks = parse(input)
+    count: dict[MemoryBlocks, int] = {}
+    for i in itertools.count():
+        if blocks in count:
+            return i - count[blocks]
+        count[blocks] = i
+        blocks = redistribute(blocks)
+    assert False  # Sanity check
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()