blob: 619c4a4387974f21693ca38fe811ee3ebcbbb0a8 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
; P09 Pack consecutive duplicates of list elements into sublists.
; If a list contains repeated elements they should be placed in separate sublists.
(def a (list "a" "a" "a" "a" "b" "c" "c" "a" "a" "d" "e" "e" "e" "e"))
; the list, the most recent value, the accumulator
(func pack-dup (lst)
(pack-dup lst "" (list)))
(func pack-dup (lst prev acc)
(branch
((empty? lst) acc) ; if we're done, return acc
((eq? (first lst) prev) ; the item is the same as the previous item
(pack-dup
(rest lst)
prev
(append ; add item to the last list in acc
(most acc)
(append
(last acc)
prev))))
(#true
(pack-dup
(rest lst)
(first lst)
(append
acc
(list (first lst))))))) ; add new list with this item
(print (->string a))
(print (->string (pack-dup a)))
|
