2_63.scm

; a) both tree->list-1 and tree->list-2 always produce one and the
; same list, namely sorted list of all entries. That means that for
; all trees from figure 2.16 result will be the same: 
; (1 3 5 7 9 11) 
;
; b) tree->list-1 have O(n log n) complexity whereas tree->list-2
; have O(n).