Added Lisp implementation for bubble sort

CONTRIBUTORS.md

@@ -57,3 +57,5 @@ NIFR91
 Michal Hanajik
 <br>
 Bendik Samseth
+Trashtalk 
+Trashtalk 

contents/bubble_sort/code/lisp/bubble_sort.lisp

@@ -0,0 +1,18 @@
+;;;;Bubble sort implementation
+
+;;;Swaps to elements in a list (complexity: O(n))
+(defun swap (lst low high)
+ (let ((list-tail (nthcdr low lst)))
+ (rotatef (car list-tail) (elt list-tail (- high low)))
+ lst))
+
+(defun bubble_sort (lst)
+ (dotimes (m (- (length lst) 1) lst) ;loop
+ (dotimes (n (- (length lst) (+ 1 m)) lst) ;loop 
+ (if (> (nth n lst) (nth (+ n 1) lst)) ;if
+ (swap lst n (+ n 1)) ;then
+ lst)))) ;else
+
+;;Use of an array insead of a list would be faster
+;;The built-in sort is also quicker (sort (list 5 4 3 2 1))
+(print (bubble_sort (list 5 4 3 2 1)))