quicksort: Add quicksort algorithm

rel #2

Author: sangamcse

quicksort/Python/quicksort.py

@@ -0,0 +1,48 @@
+"""
+QuickSort Algorithm
+- If the list is empty, return the list and terminate. - (Base case)
+- Choose a pivot element in the list.
+- Take all of the elements that are less than or equal to the pivot and use
+  quicksort on them.
+- Take all of the elements that are greater than the pivot and use quicksort
+  on them.
+- Return the concatenation of the quicksorted list of elements that are less
+  than or equal to the pivot, the pivot, and the quicksorted list of elements
+  that are greater than the pivot.
+"""
+
+
+def quicksort(arr):
+    """
+    Fuction to do quicksort.
+
+    :param arr: A list of element to sort.
+    """
+    less = []
+    pivotList = []
+    more = []
+
+    if len(arr) <= 1:
+        return arr
+    else:
+        pivot = arr[0]
+        for i in arr:
+            if i < pivot:
+                less.append(i)
+            elif i > pivot:
+                more.append(i)
+            else:
+                pivotList.append(i)
+        less = quicksort(less)
+        more = quicksort(more)
+        return less + pivotList + more
+
+
+def main():
+    arr = [6, 5, 4, 3, 2, 1]
+    print('Sorted element using Quicksort: {}'.format(
+              ' '.join(map(str, quicksort(arr)))))
+
+
+if __name__ == '__main__':
+    main()