From 3b1b3fe99e6953b53a44c070d227ad36341e71c4 Mon Sep 17 00:00:00 2001
From: Botond Hende <nettingman@gmail.com>
Date: Wed, 11 Dec 2024 10:20:30 +0100
Subject: 2024 day9-10

---
 2024/day09/solve2.py | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 2024/day09/solve2.py

(limited to '2024/day09/solve2.py')

diff --git a/2024/day09/solve2.py b/2024/day09/solve2.py
new file mode 100644
index 0000000..bed2825
--- /dev/null
+++ b/2024/day09/solve2.py
@@ -0,0 +1,58 @@
+with open("input") as f:
+    data = f.read()
+
+blocks = []
+last_file_id = None
+for idx, count in enumerate(data):
+    block_char = "." if idx % 2 == 1 else str(idx // 2)
+    for ii in range(int(count)):
+        blocks.append(block_char)
+        last_file_id = block_char
+
+end_seek_idx = len(blocks) - 1
+for file in range(int(last_file_id), -1, -1):
+    file_block = str(file)
+    file_start_block = None
+    file_end_block = None
+    for idx in range(end_seek_idx, -1, -1):
+        if blocks[idx] == file_block:
+            if file_end_block is None:
+                file_end_block = idx
+        else:
+            if file_end_block is not None:
+                file_start_block = idx + 1
+                end_seek_idx = idx
+                break
+    else:
+        break
+
+    file_size = file_end_block - file_start_block + 1
+
+    empty_block_size = 0
+    for idx, block_content in enumerate(blocks):
+        if idx > end_seek_idx:
+            break
+
+        if block_content == ".":
+            empty_block_size += 1
+        else:
+            empty_block_size = 0
+
+        if empty_block_size == file_size:
+            empty_block_start = idx - file_size + 1
+            for ii in range(file_size):
+                blocks[empty_block_start + ii], blocks[file_start_block + ii] = blocks[file_start_block + ii], blocks[empty_block_start + ii]
+            break
+
+def calculate_checksum(blocks: list[str]):
+    checksum = 0
+    for index, elem in enumerate(blocks):
+        if elem == ".":
+            continue
+
+        checksum += index * int(elem)
+
+    return checksum
+
+
+print(calculate_checksum(blocks))
-- 
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