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

* Simplify code by dropping support for legacy Python

* sort() --> sorted()

data_structures/linked_list/doubly_linked_list.py

@@ -4,14 +4,13 @@
 - Each link references the next link and the previous one.
 - A Doubly Linked List (DLL) contains an extra pointer, typically called previous pointer, together with next pointer and data which are there in singly linked list.
  - Advantages over SLL - IT can be traversed in both forward and backward direction.,Delete operation is more efficent'''
-from __future__ import print_function
 
 
 class LinkedList:           #making main class named linked list
     def __init__(self):
         self.head = None
         self.tail = None
-        
+
     def insertHead(self, x):
         newLink = Link(x)                            #Create a new link with a value attached to it
         if(self.isEmpty() == True):                  #Set the first element added to be the tail
@@ -20,52 +19,52 @@ class LinkedList:           #making main class named linked list
             self.head.previous = newLink             # newLink <-- currenthead(head)
         newLink.next = self.head                     # newLink <--> currenthead(head)
         self.head = newLink                          # newLink(head) <--> oldhead
-    
+
     def deleteHead(self):
         temp = self.head
-        self.head = self.head.next                   # oldHead <--> 2ndElement(head) 
+        self.head = self.head.next                   # oldHead <--> 2ndElement(head)
         self.head.previous = None                    # oldHead --> 2ndElement(head) nothing pointing at it so the old head will be removed
         if(self.head is None):
             self.tail = None                         #if empty linked list
         return temp
-    
+
     def insertTail(self, x):
         newLink = Link(x)
         newLink.next = None                         # currentTail(tail)    newLink -->
         self.tail.next = newLink                    # currentTail(tail) --> newLink -->
         newLink.previous = self.tail                #currentTail(tail) <--> newLink -->
         self.tail = newLink                         # oldTail <--> newLink(tail) -->
-    
+
     def deleteTail(self):
         temp = self.tail
         self.tail = self.tail.previous              # 2ndLast(tail) <--> oldTail --> None
         self.tail.next = None                       # 2ndlast(tail) --> None
         return temp
-    
+
     def delete(self, x):
         current = self.head
-        
+
         while(current.value != x):                  # Find the position to delete
             current = current.next
-            
+
         if(current == self.head):
             self.deleteHead()
-            
+
         elif(current == self.tail):
             self.deleteTail()
-            
+
         else: #Before: 1 <--> 2(current) <--> 3
             current.previous.next = current.next # 1 --> 3
             current.next.previous = current.previous # 1 <--> 3
-    
+
     def isEmpty(self):                               #Will return True if the list is empty
         return(self.head is None)
-        
+
     def display(self):                                #Prints contents of the list
         current = self.head
         while(current != None):
             current.displayLink()
-            current = current.next  
+            current = current.next
         print()
 
 class Link:

data_structures/linked_list/singly_linked_list.py

@@ -1,6 +1,3 @@
-from __future__ import print_function
-
-
 class Node:  # create a Node
     def __init__(self, data):
         self.data = data  # given data
@@ -10,7 +7,7 @@ class Node:  # create a Node
 class Linked_List:
     def __init__(self):
         self.Head = None    # Initialize Head to None
-        
+
     def insert_tail(self, data):
         if(self.Head is None): self.insert_head(data)    #If this is first node, call insert_head
         else:
@@ -37,7 +34,7 @@ class Linked_List:
             self.Head = self.Head.next
             temp.next = None
         return temp
-        
+
     def delete_tail(self):  # delete from tail
         tamp = self.Head
         if self.Head != None:
@@ -46,7 +43,7 @@ class Linked_List:
             else:
                 while tamp.next.next is not None:  # find the 2nd last element
                     tamp = tamp.next
-                tamp.next, tamp = None, tamp.next    #(2nd last element).next = None and tamp = last element 
+                tamp.next, tamp = None, tamp.next    #(2nd last element).next = None and tamp = last element
         return tamp
 
     def isEmpty(self):
@@ -79,7 +76,7 @@ def main():
     print("\nPrint List : ")
     A.printList()
     print("\nInserting 1st at Tail")
-    a3=input()    
+    a3=input()
     A.insert_tail(a3)
     print("Inserting 2nd at Tail")
     a4=input()
@@ -96,6 +93,6 @@ def main():
     A.reverse()
     print("\nPrint List : ")
     A.printList()
-    
+
 if __name__ == '__main__':
 	main()