Kiranmayep

circular_linked_list/circular_linked_list.py

@@ -0,0 +1,204 @@
+class Node: 
+    def __init__(self, data): 
+        self.data = data 
+        self.next = None
+
+class CircularLinkedList: 
+    def __init__(self): 
+        self.last = None
+
+    # This function is only for empty list 
+    def addToEmpty(self, data): 
+
+        if (self.last != None): 
+            return self.last 
+
+        # Creating the newnode temp 
+        temp = Node(data) 
+        self.last = temp 
+
+        # Creating the link 
+        self.last.next = self.last 
+        return self.last 
+
+    def addBegin(self, data): 
+
+        if (self.last == None): 
+            return self.addToEmpty(data) 
+
+        temp = Node(data) 
+        temp.next = self.last.next
+        self.last.next = temp 
+
+        return self.last 
+
+    def addEnd(self, data): 
+
+        if (self.last == None): 
+            return self.addToEmpty(data) 
+
+        temp = Node(data) 
+        temp.next = self.last.next
+        self.last.next = temp 
+        self.last = temp 
+
+        return self.last 
+
+    def addAfter(self, data, item): 
+
+        if (self.last == None): 
+            return None
+
+        temp = Node(data) 
+        p = self.last.next
+        while p: 
+            if (p.data == item): 
+                temp.next = p.next
+                p.next = temp 
+
+                if (p == self.last): 
+                    self.last = temp 
+                    return self.last 
+                else: 
+                    return self.last 
+            p = p.next
+            if (p == self.last.next): 
+                print(item, "not present in the list") 
+                break
+
+    def traverse(self): 
+        if (self.last == None): 
+            print("List is empty") 
+            return
+
+        temp = self.last.next
+        while temp: 
+            print(temp.data, end = " ") 
+            temp = temp.next
+            if temp == self.last.next: 
+                break
+
+# Driver Code 
+if __name__ == '__main__': 
+
+    llist = CircularLinkedList() 
+
+    last = llist.addToEmpty(6) 
+    last = llist.addBegin(4) 
+    last = llist.addBegin(2) 
+    last = llist.addEnd(8) 
+    last = llist.addEnd(12) 
+    last = llist.addAfter(10,8) 
+
+    llist.traverse() 
+
+# Python program to delete a given key from 
+# linked list. 
+
+# Node of a doubly linked list  
+class Node:  
+    def __init__(self, next = None, data = None):  
+        self.next = next
+        self.data = data  
+
+# Function to insert a node at the beginning of  
+# a Circular linked list  
+def push(head_ref, data): 
+
+    # Create a new node and make head as next 
+    # of it. 
+    ptr1 = Node() 
+    ptr1.data = data 
+    ptr1.next = head_ref 
+
+    # If linked list is not None then set the  
+    # next of last node  
+    if (head_ref != None) : 
+
+        # Find the node before head and update 
+        # next of it. 
+        temp = head_ref 
+        while (temp.next != head_ref): 
+            temp = temp.next
+        temp.next = ptr1 
+
+    else: 
+        ptr1.next = ptr1 # For the first node  
+
+    head_ref = ptr1 
+    return head_ref 
+
+# Function to print nodes in a given  
+# circular linked list  
+def printList( head): 
+
+    temp = head 
+    if (head != None) : 
+        while(True) : 
+            print( temp.data, end = " ") 
+            temp = temp.next
+            if (temp == head): 
+                break
+    print() 
+
+# Function to delete a given node from the list  
+def deleteNode( head, key) : 
+
+    # If linked list is empty 
+    if (head == None): 
+        return
+
+    # If the list contains only a single node 
+    if((head).data == key and (head).next == head): 
+
+        head = None
+
+    last = head 
+    d = None
+
+    # If head is to be deleted 
+    if((head).data == key) : 
+
+        # Find the last node of the list 
+        while(last.next != head): 
+            last = last.next
+
+        # Point last node to the next of head i.e.  
+        # the second node of the list 
+        last.next = (head).next
+        head = last.next
+
+    # Either the node to be deleted is not found  
+    # or the end of list is not reached 
+    while(last.next != head and last.next.data != key) : 
+        last = last.next
+
+    # If node to be deleted was found 
+    if(last.next.data == key) : 
+        d = last.next
+        last.next = d.next
+
+    else: 
+        print("no such keyfound") 
+
+    return head 
+
+# Driver program to test above functions  
+
+# Initialize lists as empty  
+head = None
+
+# Created linked list will be 2.5.7.8.10  
+head = push(head, 2) 
+head = push(head, 5) 
+head = push(head, 7) 
+head = push(head, 8) 
+head = push(head, 10) 
+
+print("List Before Deletion: ") 
+printList(head) 
+
+head = deleteNode(head, 7) 
+
+print( "List After Deletion: ") 
+printList(head)