Solution to problem 9 in Python

src/Year_2016/P9.py

@@ -63,5 +63,56 @@ def part_1() -> None:
     print(f"The length of the file is {ans}")
 
 
+# --- Part Two ---
+
+# Apparently, the file actually uses version two of the format.
+
+# In version two, the only difference is that markers within decompressed data
+# are decompressed. This, the documentation explains, provides much more
+# substantial compression capabilities, allowing many-gigabyte files to be
+# stored in only a few kilobytes.
+
+# For example:
+
+#     (3x3)XYZ still becomes XYZXYZXYZ, as the decompressed section contains no
+# markers.
+#     X(8x2)(3x3)ABCY becomes XABCABCABCABCABCABCY, because the decompressed
+# data from the (8x2) marker is then further decompressed, thus triggering the
+# (3x3) marker twice for a total of six ABC sequences.
+#     (27x12)(20x12)(13x14)(7x10)(1x12)A decompresses into a string of A
+# repeated 241920 times.
+#     (25x3)(3x3)ABC(2x3)XY(5x2)PQRSTX(18x9)(3x2)TWO(5x7)SEVEN becomes 445
+# characters long.
+
+# Unfortunately, the computer you brought probably doesn't have enough memory
+# to actually decompress the file; you'll have to come up with another way to
+# get its decompressed length.
+
+# What is the decompressed length of the file using this improved format?
+
+
+def improved_rec_decompression(my_str: str) -> int:
+    marker = re.search(r"\(\d+x\d+\)", my_str)
+
+    if not marker:
+        return len(my_str)
+    else:
+        match_numbers = re.findall(r"\d+", marker.group())
+        chars_to_repeat, times = (int(n) for n in match_numbers)
+        start, end = marker.start(), marker.end()
+        return (
+            len(my_str[:start])
+            + times
+            * improved_rec_decompression(my_str[end : end + chars_to_repeat])
+            + improved_rec_decompression(my_str[end + chars_to_repeat :])
+        )
+
+
+def part_2() -> None:
+    ans = improved_rec_decompression(chars[0])
+    print(f"The length of the file is {ans}")
+
+
 if __name__ == "__main__":
     part_1()
+    part_2()