commit 642a48b26f8456bb31d1248ff40971f63ebe74fb
parent f391291916c9f8e9d5f72efa98efab26329732ff
Author: Yuval Langer <yuval.langer@gmail.com>
Date: Sun, 19 Mar 2023 10:19:11 +0200
Add solutions to 2.61 and 2.62, but 2.60 needs some tests and I am not sure about its solution.
Diffstat:
| M | guile.scm | | | 143 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---- |
1 file changed, 137 insertions(+), 6 deletions(-)
diff --git a/guile.scm b/guile.scm
@@ -3216,9 +3216,9 @@ Q1 - Q4 = (4 - 1, 1 - 4)
'())
((element-of-set? (car set1)
set2)
- (cons (car set1)
- (intersection-set (cdr set1)
- set2)))
+ (adjoin-set (car set1)
+ (intersection-set (cdr set1)
+ set2)))
(else (intersection-set (cdr set1)
set2))))
@@ -3230,9 +3230,9 @@ Q1 - Q4 = (4 - 1, 1 - 4)
set2)
(union-set (cdr set1)
set2))
- (else (cons (car set1)
- (union-set (cdr set1)
- set2)))))
+ (else (adjoin-set (car set1)
+ (union-set (cdr set1)
+ set2)))))
(test-begin "2.59")
(test-equal
@@ -3241,3 +3241,134 @@ Q1 - Q4 = (4 - 1, 1 - 4)
(test-end "2.59"))
(sets-stuff)
+
+;; Exercise 2.60 XXX
+
+(define (exercise-2.60)
+ ;; I don't get it. Am I supposed to let these sets explode by just appending
+ ;; more and more stuff to them?
+
+ (define (element-of-set? x set)
+ (cond
+ ((null? set) #f)
+ ((equal? x (car set)) #t)
+ (else (element-of-set? x (cdr set)))))
+
+ (define (adjoin-set x set)
+ (cons x set))
+
+ (define (union-set set1 set2)
+ (append set1 set2))
+
+ (define (intersection-set set1 set2)
+ (cond
+ ((or (null? set1)
+ (null? set2)) '())
+ ((equal? (car set1) (element-of-set? (car set1)
+ set2))
+ (adjoin-set (car set1)
+ (intersection-set (cdr set1)
+ set2)))
+ (else (intersection-set (cdr set1)
+ set2))))
+
+ (test-begin "2.60")
+ (test-end "2.60"))
+
+(exercise-2.60)
+
+(define (ordered-list-set-stuff)
+ (define (element-of-set? x set)
+ (cond
+ ((= x (car set))
+ #t)
+ ((> x (car set))
+ #f)
+ (else (element-of-set? x (cdr set)))))
+
+ (define (intersection-set set1 set2)
+ (cond
+ ((null? set1) '())
+ ((null? set2) '())
+ ((= (car set1)
+ (car set2))
+ (cons (car set1)
+ (intersection-set (cdr set1)
+ (cdr set2))))
+ ((< (car set1)
+ (car set2))
+ (intersection-set (cdr set1)
+ set2))
+ ((> (car set1)
+ (car set2))
+ (intersection-set set1
+ (cdr set2)))))
+
+ (define (adjoin-set x set)
+ (cond
+ ((null? set) (cons x '()))
+ ((< x (car set)) (cons x set))
+ ((= x (car set)) set)
+ (else (cons (car set)
+ (adjoin-set x (cdr set))))))
+
+ (define (union-set set1 set2)
+ (cond
+ ((null? set1) set2)
+ ((null? set2) set1)
+ ((< (car set1)
+ (car set2))
+ (cons (car set1)
+ (union-set (cdr set1)
+ set2)))
+ ((> (car set1)
+ (car set2))
+ (cons (car set2)
+ (union-set set1
+ (cdr set2))))
+ (else (cons (car set1)
+ (union-set (cdr set1)
+ (cdr set2))))))
+ (test-begin "2.61")
+ (test-equal
+ '(1)
+ (adjoin-set 1 '()))
+ (test-equal
+ '(1)
+ (adjoin-set 1 '(1)))
+ (test-equal
+ '(1 2)
+ (adjoin-set 1 '(2)))
+ (test-equal
+ '(1 2)
+ (adjoin-set 2 '(1)))
+ (test-equal
+ '(1 2 3 4 5 6)
+ (adjoin-set 3 '(1 2 4 5 6)))
+ (test-end "2.61")
+
+ (test-begin "2.62")
+ (test-equal
+ '()
+ (union-set '() '()))
+ (test-equal
+ '(1)
+ (union-set '(1) '()))
+ (test-equal
+ '(1)
+ (union-set '() '(1)))
+ (test-equal
+ '(1)
+ (union-set '(1) '(1)))
+ (test-equal
+ '(1 2)
+ (union-set '(1 2) '(1)))
+ (test-equal
+ '(1 2)
+ (union-set '(1) '(1 2)))
+ (test-equal
+ '(1 2 3)
+ (union-set '(2 3) '(1 2 3)))
+ (test-end "2.62"))
+
+(ordered-list-set-stuff)
