; missionaries and cannibals problem
;
; This is the code that we wrote in class on 9/6/02 for the
; missionaries and cannibals problem.  We'll finish this up in the
; coming week.

(define start-state '(left 3 3 0 0))
(define goal-state '(right 0 0 3 3))

(define boat-side first)
(define l-miss second)
(define l-cann third)
(define r-miss fourth)
(define r-cann fifth)

; node: (<state> <parent>)
; root node: (<state> ())
(define node:state first)
(define node:parent second)

(define start-node (list start-state '()))

(define (mc-goal? n)
  (equal? (node:state n) goal-state))

(define (mc-children n)
; take state of n
; generate children of that state
; turn those state into nodes

() ; this is here just so that the file will load into Scheme as is
)

(define (mcs-children s)
(); this is here just so that the file will load into Scheme as is
  )

; assume boat on left
(define (mcs-boat-trip s)
  (do-trip s
	   '((-2 0 2 0)
	     (0 -2 -2)
	     (-1 0 1 0)
	     (0 -1 0 1)
	     (-1 -1 1 1)))))
(define (do-trip s additions-list)
  (if (null? additions-list)
      '()
      (cons (list (boat-side s)
		  (+ (l-miss s)
		     (first
		      (first additions-list)))
		  (+ (l-cann s)
		     (second
		      (first additions-list)))
		  (+ (r-miss s)
		     (third
		      (first additions-list)))
		  (+ (r-cann s)
		     (first
		      (first additions-list))))
	    (do-trip s (cdr additions-list)))))