;; The first three lines of this file were inserted by DrScheme. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-intermediate-lambda-reader.ss" "lang")((modname merge_sort) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "draw.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp")))))
;; Exercise  26.1.2.
;; contract: list of numbers -> list of lists of numbers
;; the function takes a list and produces a list of lists 
;; in which every list contains exactly one element of the 
;; given list
(define (make-singles lon)
  (cond
    [(empty? lon) empty]
    [else
     (cons (list (first lon))
           (make-singles (rest lon))
     )
    ]
  )
)


(check-expect (make-singles (list 2 5 9 3))
        (list (list 2) (list 5) (list 9) (list 3)))


(define (merge lon1 lon2)
  (cond [(empty? lon1) lon2]
        [(empty? lon2) lon1]
        [(< (first lon1) (first lon2)) (cons (first lon1) (merge (rest lon1) lon2))]
        [else (cons (first lon2) (merge lon1 (rest lon2)))])
)

(check-expect (merge (list 1 4 5) (list 2 3 6)) (list 1 2 3 4 5 6))

;; contract: list of lists -> list of lists
;; Write the purpose. Any assumptions that we need to make? 
;(define (merge-all-neighbors lol)
   
;)


;(check-expect (merge-all-neighbors (list (list 2) (list 5) (list 9) (list 3)))
;        (list (list 2 5) (list 3 9)))

;(check-expect (merge-all-neighbors (list (list 2 5) (list 3 9)))
;        (list (list 2 3 5 9)))

;(check-expect (merge-all-neighbors (list (list 2 5) (list 3 9) (list 7 8)))
 ;       (list (list 2 3 5 9) (list 7 8)))


;(check-expect 
; (merge-sort (list 1 6 3 5 7 4 2)) 
; (list 1 2 3 4 5 6 7))