+#lang racket
+
+(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)) '())
+ ((element-of-set? (car set1) set2) (cons (car set1) (intersection-set (cdr set1) set2)))
+ (else (intersection-set (cdr set1) set2))))
+
+#|
+ union-set and adjoin-set has changed. Rest remain unchanged.
+
+ Performance while adding a new element is O(1). Same with union.
+ intersection-set remains the same - O(m * n).
+ element-of-set? also remains the same - O (n).
+
+If duplicates are allowed, then Intersection and element-of-set? performance will degrade.
+
+|#
+
+
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