Simplify code by dropping support for legacy Python (#1143)

* Simplify code by dropping support for legacy Python

* sort() --> sorted()

data_structures/stacks/balanced_parentheses.py

@@ -1,6 +1,3 @@
-from __future__ import print_function
-from __future__ import absolute_import
-
 from .stack import Stack
 
 __author__ = 'Omkar Pathak'

data_structures/stacks/infix_to_postfix_conversion.py

@@ -1,5 +1,3 @@
-from __future__ import print_function
-from __future__ import absolute_import
 import string
 
 from .stack import Stack

data_structures/stacks/next_greater_element.py

@@ -1,17 +1,16 @@
-from __future__ import print_function
 # Function to print element and NGE pair for all elements of list
 def printNGE(arr):
- 
+
     for i in range(0, len(arr), 1):
- 
+
         next = -1
         for j in range(i+1, len(arr), 1):
             if arr[i] < arr[j]:
                 next = arr[j]
                 break
-             
+
         print(str(arr[i]) + " -- " + str(next))
- 
+
 # Driver program to test above function
 arr = [11,13,21,3]
 printNGE(arr)

data_structures/stacks/stack.py

@@ -1,4 +1,3 @@
-from __future__ import print_function
 __author__ = 'Omkar Pathak'
 
 

data_structures/stacks/stock_span_problem.py

@@ -6,7 +6,6 @@ The span Si of the stock's price on a given day i is defined as the maximum
 number of consecutive days just before the given day, for which the price of the stock
 on the current day is less than or equal to its price on the given day.
 '''
-from __future__ import print_function
 def calculateSpan(price, S):
 
     n = len(price)