Added quick sort python code

sorting/quick_sort.py

@@ -0,0 +1,42 @@
+
+def quickSort(alist):
+
+ quickSortHelper(alist,0,len(alist)-1)
+
+def quickSortHelper(alist,first,last):
+
+ if first<last:
+ splitpoint = partition(alist,first,last)
+ quickSortHelper(alist,first,splitpoint-1)
+ quickSortHelper(alist,splitpoint+1,last)
+
+def partition(alist,first,last):
+
+ pivotvalue = alist[first]
+ leftmark = first+1
+ rightmark = last
+ done = False
+
+ while not done:
+ while leftmark <= rightmark and alist[leftmark] <= pivotvalue:
+ leftmark = leftmark + 1
+
+ while alist[rightmark] >= pivotvalue and rightmark >= leftmark:
+ rightmark = rightmark -1
+
+ if rightmark < leftmark:
+ done = True
+ else:
+ temp = alist[leftmark]
+ alist[leftmark] = alist[rightmark]
+ alist[rightmark] = temp
+
+ temp = alist[first]
+ alist[first] = alist[rightmark]
+ alist[rightmark] = temp
+
+ return rightmark
+
+alist = [54,26,93,17,77,31,44,55,20]
+quickSort(alist)
+print(alist)