95 lines
1.8 KiB
Python
95 lines
1.8 KiB
Python
import sys
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# PART 1
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class Stream:
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def __init__(self, string):
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self.content = list(string)
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self.content.reverse()
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def peek(self):
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return self.content[-1]
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def pop(self):
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return self.content.pop()
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def load_groups(filename):
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groups = []
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with open(filename, "r") as f:
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for line in f:
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stream = Stream(line[:-1])
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group, garbage = parse_group(stream)
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groups.append((group, garbage))
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return groups
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def parse_group(stream):
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assert stream.pop() == "{"
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if stream.peek() == "}":
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assert stream.pop() == "}"
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return [], 0
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groups = []
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garbage = 0
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while True:
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# Determine which sub-parser to use
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if stream.peek() == "{":
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group, more_garbage = parse_group(stream)
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groups.append(group)
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garbage += more_garbage
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elif stream.peek() == "<":
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garbage += parse_garbage(stream)
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else:
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raise Exception("Incorrectly formatted input")
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# Determine whether to stop parsing
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if stream.peek() == "}":
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break
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elif stream.peek() == ",":
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assert stream.pop() == ","
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else:
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raise Exception("Incorrectly formatted input")
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assert stream.pop() == "}"
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return groups, garbage
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def parse_garbage(stream):
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assert stream.pop() == "<"
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escaped = False
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garbage = 0
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while True:
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if escaped:
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stream.pop()
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escaped = False
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elif stream.peek() == "!":
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assert stream.pop() == "!"
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escaped = True
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elif stream.peek() == ">":
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break
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else:
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stream.pop()
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garbage += 1
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assert stream.pop() == ">"
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return garbage
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def group_score(group, level=1):
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return sum(group_score(subgroup, level + 1) for subgroup in group) + level
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# PART 2
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def main(filename):
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print(f"Solutions for {filename}")
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groups = load_groups(filename)
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for group, garbage in groups:
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score = group_score(group)
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print(f"Part 1: {score}")
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print(f"Part 2: {garbage}")
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if __name__ == "__main__":
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for filename in sys.argv[1:]:
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main(filename)
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