1 files changed, 62 insertions, 0 deletions
diff --git a/2024/09/python.py b/2024/09/python.py
new file mode 100755
index 0000000..1cf450e
--- /dev/null
+++ b/2024/09/python.py
@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+
+from fileinput import input
+
+disk = list(input())[0].strip()
+
+id_ = -1
+blocks = []
+tail = 0
+file = True
+for c in disk:
+    blocks.append([tail, tail + int(c), (id_ := id_ + 1) if file else -1])
+    tail += int(c)
+    file = not file
+
+
+def expand(bs):
+    return [x for a, b, x in sorted(bs) for _ in range(b - a)]
+
+
+def debug(bs):
+    print("".join(str(b) if b != -1 else "." for b in expand(bs)))
+
+
+# Silver
+expanded = expand(blocks)
+tail = len(expanded) - 1
+fill = expanded.index(-1)
+while fill < tail:
+    expanded[fill] = expanded[tail]
+    expanded[tail] = -1
+    while expanded[tail] == -1:
+        tail -= 1
+    while expanded[fill] != -1:
+        fill += 1
+silver = sum(idx * n for idx, n in enumerate(expanded) if n != -1)
+
+
+# Gold
+for move in blocks[::-1]:
+    print(move)
+    ma, mb, mx = move
+    if mx == -1:
+        continue
+    mlen = mb - ma
+    for tidx, to in enumerate(blocks):
+        ta, tb, tx = to
+        if ta >= ma:
+            break
+        if tx != -1:
+            continue
+        if (tlen := tb - ta) < mlen:
+            continue
+        move[2] = -1
+        to[2] = mx
+        to[1] = ta + mlen
+        blocks.insert(tidx + 1, [ta + mlen, tb, -1])
+        break
+gold = sum(idx * n for idx, n in enumerate(expand(blocks)) if n != -1)
+
+print("silver:", silver)
+print("gold:", gold)