AoC day 9

2024/day09/day09.py

@@ -0,0 +1,79 @@
+import sys, os
+sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'common'))
+from common import open_file, print_and_verify_answer
+
+def run_part_one(mode, expected = None):
+    data_file = open_file( mode + ".txt")
+    input = "".join(line.strip() for line in data_file)
+    disk_array = []
+    current_block_index = 0
+    for i in range(0, len(input)):
+        if i % 2 == 1:
+            disk_array.extend(['.'] * int(input[i]))
+        else: 
+            block_size = int(input[i])
+            disk_array.extend([(current_block_index, block_size)] * block_size)
+            current_block_index += 1
+
+    last_non_dot_index = len(disk_array) - 1
+    for char_index in range(len(disk_array)):
+        if disk_array[char_index] == '.':
+            while disk_array[last_non_dot_index] == '.' and last_non_dot_index > char_index:
+                last_non_dot_index -= 1
+            if last_non_dot_index > char_index:
+                disk_array[char_index], disk_array[last_non_dot_index] = disk_array[last_non_dot_index], '.'
+                last_non_dot_index -= 1
+
+    disk_array = [char for char in disk_array if char != '.'] # strip dots
+    calculated_checksum = sum(index * block_id for index, (block_id, _) in enumerate(disk_array))
+    print_and_verify_answer(mode, "one", calculated_checksum, expected)
+
+def run_part_two(mode, expected = None):
+    data_file = open_file( mode + ".txt")
+    input = "".join(line.strip() for line in data_file)
+    disk_array = []
+    current_block_index = 0
+    i = 0
+    while i < len(input):
+        if i % 2 == 1:
+            disk_array.append('.' * int(input[i]))
+        else:
+            block_size = int(input[i])
+            disk_array.append((current_block_index, 'X' * block_size))
+            current_block_index += 1
+        i += 1
+
+    max_block_id = current_block_index - 1
+    for block_id in range(max_block_id, 0, -1):
+        block_index = next((index for index, char in enumerate(disk_array) if isinstance(char, tuple) and char[0] == block_id), None)
+        if block_index is None:
+            continue
+        block_size = len(disk_array[block_index][1])
+
+        for char_index, char in enumerate(disk_array):
+            if isinstance(char, str) and len(char) >= block_size and char_index < block_index:
+                disk_array[char_index] = disk_array[block_index]
+                disk_array[block_index] = '.' * block_size
+                remaining_dots = len(char) - block_size
+                if remaining_dots > 0:
+                    disk_array.insert(char_index + 1, '.' * remaining_dots)
+                break
+
+    calculated_checksum = 0
+    file_index = 0
+    for item in disk_array:
+        if type(item) == str:
+            file_index += len(item)
+        else:
+            for _ in range(0, len(item[1])):
+                calculated_checksum += file_index*item[0]
+                file_index += 1
+
+    print_and_verify_answer(mode, "two", calculated_checksum, expected)
+
+# ADD EXPECTED OUTPUTS TO TESTS HERE 👇
+run_part_one("test", 1928)
+run_part_one("prod", 6283170117911)
+run_part_two("test", 2858)
+run_part_two("prod", 6307653242596)
+# Now run it and watch the magic happen 🪄

2024/day09/test.txt

@@ -0,0 +1 @@
+2333133121414131402

README.md

@@ -15,7 +15,7 @@ Started in 2022, but I'll backfill previous years when I need a festive boost.
 ⬜ = incomplete or not attempted  
 
 ### Stats
-**2024:**  🟧🟧🟧🟧🟧🟧🟧🟧⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(16)_  
+**2024:**  🟧🟧🟧🟧🟧🟧🟧🟧🟧⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(18)_  
 **2023:**  🟨🟨🟨🟨🟧🟨🟨🟧⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(16)_  
 **2022:**  🟨🟨🟨🟨🟨🟨🟨🟨🟨🟨🟨🟧🟨🟨⬛⬜⬜⬛⬜⬛🟨⬜🟨⬜⬛ _(36)_  
 **2021:**  🟨🟨🟨🟨🟨🟨🟨🟨⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜⬜ _(16)_