Merge pull request #95 from Iamtripathisatyam/master

Created a Swap Nodes of Linked List without Swapping data code in Python

Author: smv1999

Data Structures/Linked Lists/Swap_nodes.py

@@ -0,0 +1,90 @@
+"""
+  Given a linked list and two keys in it, swap nodes for two given keys.
+  Nodes should be swapped by changing links. 
+  Swapping data of nodes may be expensive in many situations
+  when data contains many fields. 
+                                     """
+
+
+""" 
+  Input: 8 -> 5 -> 10 -> 7 -> 6 -> 11 -> 9 -> None, key1 = 8, key2 = 5
+  Output: 5 -> 8 -> 10 -> 7 -> 6 -> 11 -> 9 -> None4
+
+"""
+
+# Class to create new Node
+
+
+class Node:
+    def __init__(self, data):
+        self.data = data
+        self.next = None
+
+
+class Linked_List:
+    def __init__(self):
+        self.head = None
+
+    # Function to add the data at the end of linked list
+    def Insert_At_End(self, new_data):
+        new_node = Node(new_data)  # Allocate the new node and put the data
+        if self.head is None:  # if list is empty then retrun
+            self.head = new_node
+            return
+        current = self.head
+        while(current.next):
+            current = current.next
+        current.next = new_node  # Move new node to the next of current node
+
+# Fucntion to swap nodes key1 and key2 in linked list by changing links
+    def Swap(self, key1, key2):
+        Prev_node_1 = None
+        Prev_node_2 = None
+        Node_1 = self.head
+        Node_2 = self.head
+        if self.head == None:
+            return
+
+        if key1 == key2:  # Nothing to do if key1 and key2 are same
+            return
+        while(Node_1.data != key1):  # Search for key 1
+            Prev_node_1 = Node_1
+            Node_1 = Node_1.next
+        while(Node_2.data != key2):  # Search for key 2
+            Prev_node_2 = Node_2
+            Node_2 = Node_2.next
+        if Prev_node_1 is not None:
+            Prev_node_1.next = Node_2
+        else:
+            self.head = Node_2
+        if Prev_node_2 is not None:
+            Prev_node_2.next = Node_1
+        else:
+            self.head = Node_1
+        temp = Node_1.next
+        Node_1.next = Node_2.next
+        Node_2.next = temp
+# Function to print the data to the screen
+
+    def Display(self):
+        temp = self.head
+        while(temp):
+            print(temp.data, "->", end=" ")
+            temp = temp.next
+        print("None")
+
+
+if __name__ == "__main__":
+    L_list = Linked_List()
+    L_list.Insert_At_End(8)
+    L_list.Insert_At_End(5)
+    L_list.Insert_At_End(10)
+    L_list.Insert_At_End(7)
+    L_list.Insert_At_End(6)
+    L_list.Insert_At_End(11)
+    L_list.Insert_At_End(9)
+    print("Linked List: ")
+    L_list.Display()
+    print("Swap List: ")
+    L_list.Swap(8, 5)
+    L_list.Display()