chore(Python): add program to print middle node element of linked list (#716)

algorithms/Python/README.md

@@ -11,6 +11,8 @@
 - [Doubly](linked_lists/doubly.py)
 - [Singly](linked_lists/singly.py)
 - [Reverse List](linked_lists/reverse-linkedlist.py)
+- [Middle Node](linked_lists/middle-node-linkedlist.py)
+
 
 ## Dictionaries
 - [Two Sum](dictionaries/two-sum.py)

algorithms/Python/linked_lists/middle-node-linkedlist.py

@@ -0,0 +1,43 @@
+#printing middle node element of linked list
+#we are using two pointer method to get the solution
+
+class Node:
+    #Constructor to build node
+    def __init__(self, data):
+        self.data = data
+        self.next = None
+
+class LinkedList:
+    #Constructor to create head node
+    def __init__(self):
+        self.head = None
+
+    #Function to push element at head (at beginning)
+    def push(self, data):
+        new_node = Node(data)
+        new_node.next = self.head
+        self.head = new_node
+    
+    #Function returns data of middle node
+    def middle_element(self):
+        if self.head is None:
+            return None
+        slow = self.head
+        fast = self.head
+        while fast and fast.next:
+            slow = slow.next
+            fast = fast.next.next
+        return slow.data
+
+if __name__=='__main__':
+    ob = LinkedList()
+    ob.push(5)
+    ob.push(4)
+    ob.push(3)
+    ob.push(2)
+    ob.push(1)
+    print(ob.middle_element())
+    
+    #list: 1->2->3->4->5 Hence middle element is 3
+
+