School Commit Init

Anul 2/Semestrul 1/Programare logica si functionala/l1.lisp

@@ -0,0 +1,90 @@
+;5.
+;a) Write twice the n-th element of a linear list. Example: for (10 20 30 40 50) and n=3 will produce (10 20 30 30 40 50).
+
+;duplicate-nth-element(l1l2...ln, n) =
+;  empty list if l1l2...ln is empty
+;  l1 + l1l2...ln if n = 1
+;  l1 + duplicate-nth-element(l2...ln, n) otherwise
+
+(defun duplicate-nth-element (lst n)
+    (cond   
+        ((null lst) nil)
+        ((< n 1 ) lst )
+        ((= n 1) (cons (car lst) lst))
+        (t (cons (car lst) (duplicate-nth-element (cdr lst) (- n 1))))
+    )
+)
+
+(print (duplicate-nth-element '(10 20 30 40 50) 3))
+(print (duplicate-nth-element '(10 20 30 40 50) 30))
+(print (duplicate-nth-element '(10 20 30 40 50) -1))
+
+
+;b) Write a function to return an association list with the two lists given as parameters.
+; Example: (A B C) (X Y Z) --> ((A.X) (B.Y) (C.Z)).
+
+;create-association-list(l1l2...ln, m1m2...mn) =
+;  empty list if l1l2...ln and m1m2...mn are empty
+;  (l1, m1) + create-association-list(l2...ln, m2...mn) otherwise
+; (l1, nil) + create-association-list(l2...ln, m1m2...mn) if m1m2...mn is empty
+; (nil, m1) + create-association-list(l1l2...ln, m2...mn) if l1l2...ln is empty
+ (defun create-association-list (list1 list2)
+  (if (and (null list1) (null list2))
+      '()
+      (let ((key (car list1))
+            (value (car list2)))
+        (cons (cons key value)
+              (create-association-list (cdr list1) (cdr list2))))))
+
+(print (create-association-list '(A B C) '(X Y Z)))
+(print (create-association-list '(A B) '(X Y Z)))
+(print (create-association-list '(A B C) '(X Y)))
+
+;c) Write a function to determine the number of all sublists of a given list, on any level. A sublist is either the list itself, or any element that is a list, at any level. Example:
+ ;(1 2 (3 (4 5) (6 7)) 8 (9 10)) => 5 lists:
+;(list itself, (3 ...), (4 5), (6 7), (9 10)).
+
+;count-sublists-helper(l1l2...ln) =
+;  0 if l1l2...ln is empty
+;  1 + count-sublists-helper(l2...ln) + count-sublists-helper(l1) if l1 is a list
+;  count-sublists-helper(l2...ln) otherwise
+(defun count-sublists-helper (lst)
+  (if (null lst)
+      0
+      (let ((head (car lst))
+            (tail (cdr lst)))
+        (if (listp head)
+            (+ 1 (count-sublists-helper head) (count-sublists-helper tail))
+            (count-sublists-helper tail)))))
+
+;count-sublists(lst) =
+;  0 if lst is empty
+;  1 + count-sublists-helper(lst) otherwise
+(defun count-sublists (lst)
+    (if (listp lst)
+    (+ 1 (count-sublists-helper lst))
+    0))
+
+
+(print (count-sublists '(1 2 (3 (4 5) (6 7)) 8 (9 10))))
+(print (count-sublists '(1 2 (3 (4 5) (6 7)) 8 (9 10) (11))))
+
+;d) Write a function to return the number of all numerical atoms in a list at superficial level.
+
+;count-numerical-atoms(l1l2...ln) =
+;  0 if l1l2...ln is empty
+;  1 + count-numerical-atoms(l2...ln) if l1 is a number
+;  count-numerical-atoms(l2...ln) otherwise
+(defun count-numerical-atoms (lst)
+  (if (null lst)
+      0
+      (let ((head (car lst))
+            (tail (cdr lst)))
+        (if (numberp head)
+            (+ 1 (count-numerical-atoms tail))
+            (count-numerical-atoms tail)))))
+
+(print(count-numerical-atoms '(1 2 (3 (4 5) (6 7)) 8 (9 10))))
+
+(exit)
+