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Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.
Solution Threads
| M | T | W | T | F | S | S |
|---|---|---|---|---|---|---|
| 1 | ||||||
| 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| 16 | 17 | 18 | 19 | 20 | 21 | 22 |
| 23 | 24 | 25 |
Icon base by Lorc under CC BY 3.0 with modifications to add a gradient
console.log('Hello World')
defmodule AdventOfCode.Solution.Year2024.Day03 do
def part1(input) do
Regex.scan(~r/mul\((?<l>\d+),(?<r>\d+)\)/, input, capture: ["l", "r"])
|> Stream.map(fn l -> Enum.reduce(l, 1, &(&2 * String.to_integer(&1))) end)
|> Enum.sum()
end
def part2(input) do
input |> String.replace(~r/don't\(\).*(do\(\)|$)/Us, "") |> part1
end
end
Just did some basic regex stuff.
Part 1 and 2
(defun p1-mult (str)
"pulls out numbers and multiplies them, assumes already filtered by size"
(let ((vals (ppcre:all-matches-as-strings "\\d+" str)))
(apply #'* (or (mapcar #'parse-integer vals) '(0)))))
(defun p1-process-line (line)
"look for mul, do the mul, and sum"
(let ((ptrn "mul\\(\\d?\\d?\\d,\\d?\\d?\\d\\)"))
(apply #'+ (mapcar #'p1-mult (ppcre:all-matches-as-strings ptrn line)))))
(defun run-p1 (file)
(let ((data (read-file file #'p1-process-line)))
(apply #'+ data)))
(defun p2-process-line (line)
"looks for mul, do, and don't"
(let ((ptrn "(mul\\(\\d?\\d?\\d,\\d?\\d?\\d\\))|(do\\(\\))|(don't\\(\\))"))
(ppcre:all-matches-as-strings ptrn line)))
(defun p2-filter (data)
"expects list containing the string tokens (mul, do, don't) from the file"
(let ((process t))
(loop for x in data
when (string= "don't()" x)
do (setf process nil)
when (string= "do()" x)
do (setf process t)
when process
sum (p1-mult x))))
(defun run-p2 (file)
(let ((data (read-file file #'p2-process-line)))
;; treat the input as one line to make processing the do's and don't's easier
(p2-filter (flatten data))))