102 lines
2.7 KiB
Python
102 lines
2.7 KiB
Python
#!/usr/bin/env python
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# https://adventofcode.com/2025/day/5
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import re, operator
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from functools import reduce
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f = open("day06input.txt", "r")
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#f = open("testinput.txt", "r")
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d = [l.strip("\n") for l in f.readlines()]
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r = re.compile("\s+")
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def get_op(s: str) -> callable:
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if s == "*":
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return operator.mul
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elif s == "+":
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return operator.add
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else:
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raise Exception("Unknown operator!")
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def prep_data(raw_data: list[str]) -> list[str]:
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# split lines
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raw_data = [r.split(l) for l in raw_data]
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# remove empty first/last element(s) if present (these occur when there are spaces before a data line's first or fater its final number/operator)
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for d in raw_data:
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if d[0] == "":
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d.pop(0)
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if d[-1] == "":
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d.pop()
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# make sure all data lines have the same length
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assert all([len(raw_data[j+1]) - len(raw_data[j]) == 0 for j in range(len(raw_data) - 1)])
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return raw_data
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def part1(data: list[str]) -> int:
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data = prep_data(data)
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total = 0
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# loop over number of elements per data line
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for i in range(len(data[0])):
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total += reduce(get_op(data[-1][i]), [int(data[j][i]) for j in range(len(data) - 1)])
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return total
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def part2(data: list[str]) -> int:
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# get length of longest number in each column
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# actually I'm counting the number of spaces between each operator but this value is equal to what we're looking for
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num_lengths = [len(x) for x in r.findall(data[-1])]
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# final num_length is too small b/c there's no single-space gap to the next element
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num_lengths[-1] += 1
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ops = prep_data([data[-1]])[0]
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total = 0
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r_left = re.compile("(^\s+)")
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r_right = re.compile("(\s+$)")
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for j in range(len(num_lengths)):
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stripes = []
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for i in range(len(data) - 1):
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# cut out correct part of data line
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d = data[i][:num_lengths[j]]
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# replace spaces with dummy character at the start of the substring
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m = r_left.search(d)
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if m:
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a, b = m.span()
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d = "X" * (b - a) + d[b:]
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# replace spaces with dummy character at the end of the substring
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m = r_right.search(d)
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if m:
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a, b = m.span()
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d = d[:a] + "X" * (b - a)
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# store the prepped substring
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stripes.append(d)
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# clip substring from data line
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data[i] = data[i][num_lengths[j]+1:]
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# calculate the actual numbers
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actual_nums = []
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for i in range(len(stripes[0])):
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num = "".join([stripes[k][i] for k in range(len(stripes))])
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actual_nums.append(int(num.strip("X")))
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# print(actual_nums)
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# print(f"{j}\t{ops[j]}\t{get_op(ops[j])}\t{reduce(get_op(ops[j]), actual_nums)}")
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total += reduce(get_op(ops[j]), actual_nums)
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return total
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print(part1(d))
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print(part2(d))
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