From 1b6502df7adc946ee998f209e71d7a0f2972efd3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20Engl=C3=B6f=20Ytterstr=C3=B6m?= <yttan@fastmail.se>
Date: Mon, 9 Dec 2024 13:30:39 +0100
Subject: [PATCH] Solve 2024:9 p1-2 "Disk Fragmenter"

Hard one. Comparing to earlier years, the
difficulty level seems higher than usual. I blame
the LLM hipsters.

This one I asumed, but missed when I tried to
find it:
> "If a block contains free space, skip it instead."

Lucky me.
---
 2024-python/aoc.py           |  6 ++--
 2024-python/output/day_09.py | 67 ++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 3 deletions(-)
 create mode 100644 2024-python/output/day_09.py

diff --git a/2024-python/aoc.py b/2024-python/aoc.py
index 1842c0a..7ee986e 100644
--- a/2024-python/aoc.py
+++ b/2024-python/aoc.py
@@ -30,11 +30,11 @@ if day_no and name:
         s.write(
             f"""
 import re
-from collections import deque, Counter
+from collections import deque, Counter, defaultdict
 from heapq import heappop, heappush
-from itertools import compress, combinations, chain
+from itertools import compress, combinations, chain, permutations
 
-from output import matrix, D, DD, ADJ, ints, mhd, mdbg, vdbg
+from output import matrix, D, DD, ADJ, ints, mhd, mdbg, vdbg, cw, ccw
 
 
 def solve(data):
diff --git a/2024-python/output/day_09.py b/2024-python/output/day_09.py
new file mode 100644
index 0000000..048d855
--- /dev/null
+++ b/2024-python/output/day_09.py
@@ -0,0 +1,67 @@
+from collections import deque
+
+
+def solve(data):
+    blocks_checksum = defrag(data)
+    files_checksum = defrag(data, True)
+    return blocks_checksum, files_checksum
+
+
+def defrag(data, move_files=False):
+    expected_seq_len = sum(map(int, data[::2]))
+    seq = dict()
+    gaps = dict()
+    q = deque([])
+    i = 0
+    for fileid, pair in enumerate(zip(data[::2], data[1::2] + "0")):
+        size, free = map(int, pair)
+        q.append((i, fileid, size))
+        for _ in range(int(size)):
+            seq[i] = fileid
+            i += 1
+        gaps[i] = free
+        i += int(free)
+    while q:
+        i, fileid, size = q.pop()
+        if move_files:
+            updated = False
+            for pos, space in gaps.items():
+                if pos > i:
+                    continue
+                if size <= space:
+                    rem = space - size
+                    updated = True
+                    break
+            if updated:
+                for k in range(size):
+                    seq[pos + k] = fileid
+                for k in range(i, i + size):
+                    del seq[k]
+                del gaps[pos]
+                gaps[pos + size] = rem
+                gaps = dict(sorted(gaps.items(), key=lambda x: x[0]))
+        else:
+            move = False
+            for j in range(size):
+                for k in range(expected_seq_len):
+                    if k not in seq:
+                        seq[k] = fileid
+                        del seq[i + j]
+                        move = True
+                        break
+            if not move:
+                break
+    return sum(
+        pos * id
+        for pos, id in enumerate(seq.get(fileid, 0) for fileid in range(max(seq) + 1))
+    )
+
+
+if __name__ == "__main__":
+    with open("./input/09.txt", "r") as f:
+        inp = f.read().strip()
+
+    p1, p2 = solve(inp)
+
+    print(p1)
+    print(p2)