Solution to problem 8 in Python

src/Year_2015/P8.py

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+# --- Day 8: Matchsticks ---
+
+# Space on the sleigh is limited this year, and so Santa will be bringing his
+# list as a digital copy. He needs to know how much space it will take up when
+# stored.
+
+# It is common in many programming languages to provide a way to escape special
+# characters in strings. For example, C, JavaScript, Perl, Python, and even PHP
+# handle special characters in very similar ways.
+
+# However, it is important to realize the difference between the number of
+# characters in the code representation of the string literal and the number of
+# characters in the in-memory string itself.
+
+# For example:
+
+#     "" is 2 characters of code (the two double quotes), but the string
+# contains zero characters.
+#     "abc" is 5 characters of code, but 3 characters in the string data.
+#     "aaa\"aaa" is 10 characters of code, but the string itself contains six
+# "a" characters and a single, escaped quote character, for a total of 7 characters in the string data.
+#     "\x27" is 6 characters of code, but the string itself contains just one
+# - an apostrophe ('), escaped using hexadecimal notation.
+
+# Santa's list is a file that contains many double-quoted string literals, one
+# on each line. The only escape sequences used are \\ (which represents a
+# single backslash), \" (which represents a lone double-quote character), and
+# \x plus two hexadecimal characters (which represents a single character with
+# that ASCII code).
+
+# Disregarding the whitespace in the file, what is the number of characters of
+# code for string literals minus the number of characters in memory for the
+# values of the strings in total for the entire file?
+
+# For example, given the four strings above, the total number of characters of
+# string code (2 + 5 + 10 + 6 = 23) minus the total number of characters in
+# memory for string values (0 + 3 + 7 + 1 = 11) is 23 - 11 = 12.
+
+with open("files/P8.txt") as f:
+    lines = [line for line in f.read().strip().split()]
+
+
+# TIL: eval()
+def part_1() -> None:
+    res = sum(len(line) - len(eval(line)) for line in lines)
+
+    print(f"There are {res} characters.")
+
+
+# --- Part Two ---
+
+# Now, let's go the other way. In addition to finding the number of characters
+# of code, you should now encode each code representation as a new string and
+# find the number of characters of the new encoded representation, including
+# the surrounding double quotes.
+
+# For example:
+
+#     "" encodes to "\"\"", an increase from 2 characters to 6.
+#     "abc" encodes to "\"abc\"", an increase from 5 characters to 9.
+#     "aaa\"aaa" encodes to "\"aaa\\\"aaa\"", an increase from 10 characters to
+# 16.
+#     "\x27" encodes to "\"\\x27\"", an increase from 6 characters to 11.
+
+# Your task is to find the total number of characters to represent the newly
+# encoded strings minus the number of characters of code in each original
+# string literal. For example, for the strings above, the total encoded length
+# (6 + 9 + 16 + 11 = 42) minus the characters in the original code
+# representation (23, just like in the first part of this puzzle) is
+# 42 - 23 = 19.
+
+
+def part_2() -> None:
+    # 2 for the ""
+    # just count numbers of \\ and new "
+    res = sum(2 + line.count("\\") + line.count('"') for line in lines)
+
+    print(f"There are {res} characters.")
+
+
+if __name__ == "__main__":
+    part_1()
+    part_2()