Partial progress: AoC 2015 Day 2, Part 1 done

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+;;;; 2015.02.01-first-attempt.lisp
+;;;; Advent of Code 2015
+;;;; Day 2: I Was Told There Would Be No Math
+;;;; Attempt 1: First attempt in Common Lisp
+
+;; ---------------------------------------------------------------------
+;;; Package Definition
+;; ---------------------------------------------------------------------
+
+(ql:quickload :cl-ppcre)
+(ql:quickload :alexandria)
+
+(defpackage :2015-02-01-first-attempt
+  (:use #:common-lisp
+        #:cl-ppcre
+        #:alexandria))
+(in-package :2015-02-01-first-attempt)
+
+
+
+
+;; ---------------------------------------------------------------------
+;;; Definitions
+;; ---------------------------------------------------------------------
+
+(defconstant +PUZZLE-INPUT-FILE+ "~/proj/Learn/aoc/src/2015.02._PUZZLE-INPUT.txt"
+  "File to be used as input to the program.")
+
+(defconstant +PUZZLE-INPUT-STRING+ (uiop:read-file-string +PUZZLE-INPUT-FILE+)
+  "Single-string version of the text in `+PUZZLE-INPUT-FILE+'.")
+
+(defconstant +PUZZLE-INPUT-STRING-LIST+
+  (loop for line in (ppcre:split #\Newline +PUZZLE-INPUT-STRING+)
+        collect (ppcre:all-matches-as-strings "-?\\d+" line))
+  "List of sublists containing string versions of the dimensions of presents.")
+
+(defconstant +PUZZLE-INPUT-LIST+
+  (loop for sublist in +PUZZLE-INPUT-STRING-LIST+
+        collect (mapcar #'parse-integer sublist))
+  "A list of presents and their numerical dimensions.
+Represented as a list of sublists, with each sublist containing the 3
+dimensions of a particular present.")
+
+
+
+
+;; ---------------------------------------------------------------------
+;;; Part 1
+;; -------
+;; The elves are running low on wrapping paper, and so they need to
+;; submit an order for more. They have a list of the dimensions
+;; (length l, width w, and height h) of each present, and only want to
+;; order exactly as much as they need.
+;;
+;; Fortunately, every present is a box (a perfect right rectangular
+;; prism), which makes calculating the required wrapping paper for each
+;; gift a little easier: find the surface area of the box, which is
+;; 2*l*w + 2*w*h + 2*h*l. The elves also need a little extra paper for
+;; each present: the area of the smallest side.
+;;
+;; For example:
+;;
+;;     A present with dimensions 2x3x4 requires 2*6 + 2*12 + 2*8 = 52
+;;     square feet of wrapping paper plus 6 square feet of slack, for a
+;;     total of 58 square feet.
+;;
+;;     A present with dimensions 1x1x10 requires 2*1 + 2*10 + 2*10 = 42
+;;     square feet of wrapping paper plus 1 square foot of slack, for a
+;;     total of 43 square feet.
+;;
+;; All numbers in the elves' list are in feet. How many total square
+;; feet of wrapping paper should they order?
+;; ---------------------------------------------------------------------
+
+
+(defun smallest-two (DIMENSIONS)
+  "Return the smallest 2 `DIMENSIONS', assuming there are 3."
+  (cdr (sort DIMENSIONS #'>)))
+
+(defun wrapping-paper-area (DIMENSIONS)
+  "Calculate the amount of paper needed for a present with `DIMENSIONS'.
+`DIMENSIONS' is assumed to be a list with 3 elements representing the
+length, width, and height of a particular present."
+  (+ (apply #'+ (list (* 2 (first DIMENSIONS) (second DIMENSIONS))
+                      (* 2 (first DIMENSIONS) (third DIMENSIONS))
+                      (* 2 (second DIMENSIONS) (third DIMENSIONS))))
+     (apply #'* (smallest-two DIMENSIONS))))
+
+;; Test single-present examples from problem text
+(assert (= 58 (wrapping-paper-area '(2 3 4))))
+(assert (= 43 (wrapping-paper-area '(1 1 10))))
+
+(defun wrapping-paper-total (PRESENTS)
+  "Calculate the total amount of wrapping paper needed for the entire list of `PRESENTS'.
+`PRESENTS' is assumed to be a list of sublists of 3
+elements each, representing the dimensions of each present."
+  (apply #'+ (mapcar #'wrapping-paper-area PRESENTS)))
+
+;; Test correct answer
+(assert (= 1586300 (wrapping-paper-total +PUZZLE-INPUT-LIST+)))
+
+
+
+
+;; ---------------------------------------------------------------------
+;;; Part 2
+;; -------
+;; The elves are also running low on ribbon. Ribbon is all the same
+;; width, so they only have to worry about the length they need to
+;; order, which they would again like to be exact.
+;;
+;; The ribbon required to wrap a present is the shortest distance around
+;; its sides, or the smallest perimeter of any one face. Each present
+;; also requires a bow made out of ribbon as well; the feet of ribbon
+;; required for the perfect bow is equal to the cubic feet of volume of
+;; the present. Don't ask how they tie the bow, though; they'll never
+;; tell.
+;;
+;; For example:
+;;
+;;     A present with dimensions 2x3x4 requires 2+2+3+3 = 10 feet of
+;;     ribbon to wrap the present plus 2*3*4 = 24 feet of ribbon for the
+;;     bow, for a total of 34 feet.
+;;
+;;     A present with dimensions 1x1x10 requires 1+1+1+1 = 4 feet of
+;;     ribbon to wrap the present plus 1*1*10 = 10 feet of ribbon for
+;;     the bow, for a total of 14 feet.
+;;
+;; How many total feet of ribbon should they order?
+;; ---------------------------------------------------------------------