;;;  flashlight.scm    Dave Reed    10/04/04

(require (lib "list.ss"))
(require (lib "compat.ss"))

(define (GET-MOVES state)
  
   (define (all-pairs lst)
      (define (pair-up item lst)
        (if (null? lst)
            '()
            (cons (list item (car lst)) (pair-up item (cdr lst)))))  
      (cond ((< (length lst) 2) '())
            ((= (length lst) 2) (list lst))
            (else (append (pair-up (car lst) (cdr lst))
                          (all-pairs (cdr lst))))))
  
  (define (all-moves move-list)
      (if (null? move-list)
          '()
          (cons (list (if (equal? (cadr state) 'left)
                          (list (remove-all (car move-list) (car state))
                                'right
                                (sort < (append (caddr state) (car move-list))))
                          (list (sort < (append (car state) (car move-list)))
                                'left
                                (remove-all (car move-list) (caddr state))))
                      (apply max (car move-list)))
                (all-moves (cdr move-list)))))
  
  (if (equal? (cadr state) 'left)
      (all-moves (append (map list (car state)) (all-pairs (car state))))
      (all-moves (append (map list (caddr state)) (all-pairs (caddr state))))))


(define (remove-all del-list arblist)
  (cond ((null? arblist) '())
        ((member (car arblist) del-list) (remove-all del-list (cdr arblist)))
        (else (cons (car arblist) (remove-all del-list (cdr arblist))))))

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;;; ORIGINAL VERSION: COUNT NUMBER OF PEOPLE OUT OF POSITION
(define (H state goalState)
  (+ (length (remove-all (car goalState) (car state)))
     (length (remove-all (caddr goalState) (caddr state)))))