Day 3: Mull It Over
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Lisp
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))))
