Racket implementation for Bubble Sort (#164)

* Added racket lang in book.json.

* Added bubbleSort.rkt

* Update bubble_sort.md

* Update CONTRIBUTORS.md

Author: Unlambder

CONTRIBUTORS.md

@@ -9,3 +9,4 @@ Maxime Dherbécourt
 Jess 3Jane
 Pen Pal
 Chinmaya Mahesh
+Unlambder

book.json

@@ -82,6 +82,10 @@
 				{
 					"lang": "go",
 					"name": "Go"
+				},
+				{
+					"lang": "racket",
+					"name": "Racket"
 				}
 				{
 					"lang": "m",

chapters/sorting_searching/bubble/bubble_sort.md

@@ -32,6 +32,8 @@ This means that we need to go through the vector $$\mathcal{O}(n^2)$$ times with
 [import:3-18, lang:"d"](code/d/bubble_sort.d)
 {% sample lang="go" %}
 [import:7-21, lang:"go"](code/go/bubbleSort.go)
+{% sample lang="racket" %}
+[import:5-19, lang:"racket"](code/racket/bubbleSort.rkt)
 {% endmethod %}
 
 ... And that's it for the simplest bubble sort method.

chapters/sorting_searching/bubble/code/racket/bubbleSort.rkt

@@ -0,0 +1,21 @@
+#lang racket
+
+(provide bubbleSort)
+
+
+(define bubbleSort
+  (case-lambda [(l) (bubbleSort l (length l))]
+               [(l n) (if (= n 1)
+                          l
+                          (bubbleSort (pass l 0 n) (- n 1)))]))
+
+; a single pass, if this is the nth pass, then we know that the (n - 1) last elements are already sorted
+(define (pass l counter n)
+  (let ([x (first l)]
+        [y (second l)]
+        [r (drop l 2)])
+    (cond [(= (- n counter) 2) (cons (min x y) (cons (max x y) r))]
+          [(cons (min x y) (pass  (cons (max x y) r) (+ counter 1) n))])))
+          
+
+((lambda (x) (display (bubbleSort x))) (read))