Attempt to solve the stacking boxes problem

Stacking-boxes.clj

(ns user.core
  (:use [clojure.contrib.duck-streams :only (read-lines)]))

(declare lcs) ; Declare the memoized lcs

(def *file-name* "/Users/svdberg/boxes.txt")

(defn longest [xs ys] (if (> (count xs) (count ys)) xs ys))
 
(defn undecorated-lcs [seqx seqy]
    (cond (empty? seqx) seqx 
	  (empty? seqy) seqy
	  true (let [[x & xs] (seq seqx), [y & ys] (seq seqy)]
		    (if (= x y)
			(cons x (lcs xs ys))
			(longest (lcs seqx ys) (lcs xs seqy))))))
 
; Make a memoized version of lcs
(def lcs (memoize undecorated-lcs))

(defn number-a-seq
  [seq]
  (map-indexed (fn [a b] {:index a :seq b}) seq))

(defn compare-func
  "input: 2 seq of equal size, output: -1 if  a<b, 0 iff a==b, 1 if a>b"
  [list-a list-b]
  (compare list-a list-b))

(defn seq-sel
  [a]
  (:seq a))

(defn sort-numbered-sequence
  "sort a sequence in the form {index: 1 seq: [1 2 3]}"
  [num-seq]
  (let [key-fn seq-sel
        comp-fn compare-func]
    (sort-by key-fn compare-func num-seq)))

;; read the file
(defn get-boxes
  "read the boxes from a textfile, returning a list of lists"
  []
  (let [file-lines (read-lines *file-name*)
        string-seq (map #(re-seq #"[\d.]+" % ) file-lines)
        config-line (map read-string (first string-seq))
        dimension (last config-line)
        nr-of-boxes (first config-line)
        boxes (take nr-of-boxes (drop 1 string-seq))]
    (vec (map #(vec (map (fn [a]  (read-string a)) % )) boxes))))

(defn normalized-boxes
  []
  (vec (sort (vec (map #(vec (sort %)) (get-boxes))))))

(defn transpose
  "rotates a matrix such that rows become columns"
  [matrix]
  (vec (apply map vector matrix)))


;; wrong approach.. ?
(defn lis-seq
  []
  (let [bb (get-boxes)
        sbb (vec (map #(vec (sort %)) bb))
        sns (sort-numbered-sequence (number-a-seq sbb))]
    (map (fn [a] (lcs (nth bb (:index a)) (:seq a))) sns)))