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# Python Program For Cloning A Linked List With Next And Random Pointer- Set 2

We have already discussed 2 different ways to clone a linked list. In this post, one more simple method to clone a linked list is discussed.

The idea is to use Hashing. Below is algorithm.

1. Traverse the original linked list and make a copy in terms of data.
2. Make a hash map of key value pair with original linked list node and copied linked list node.
3. Traverse the original linked list again and using the hash map adjust the next and random reference of cloned linked list nodes.

Below is the implementation of above approach.

## Python3

 `# Python3 program to clone a linked list  ` `# with random pointers  ` `class` `Node:  ` `    ``def` `__init__(``self``, data): ` `         `  `        ``# Node Data ` `        ``self``.data ``=` `data  ` `         `  `        ``# Node Next ` `        ``self``.``next` `=` `None`  `         `  `        ``# Node Random ` `        ``self``.random ``=` `None`  ` `  `# Dictionary ` `class` `MyDictionary(``dict``):  ` ` `  `    ``# __init__ function ` `    ``def` `__init__(``self``): ` `         `  `        ``super``().__init__() ` `        ``self` `=` `dict``() ` ` `  `        ``# Function to add key:value ` `        ``def` `add(``self``, key, value): ` `         `  `        ``# Adding Values to dictionary ` `        ``self``[key] ``=` `value  ` ` `  `# Linked list class  ` `class` `LinkedList: ` `     `  `    ``# Linked list constructor ` `    ``def` `__init__(``self``, node): ` `        ``self``.head ``=` `node ` ` `  `    ``# Method to print the list. ` `    ``def` `__repr__(``self``): ` `         `  `        ``temp ``=` `self``.head ` `        ``while` `temp ``is` `not` `None``: ` `            ``random ``=` `temp.random ` `            ``random_data ``=` `(random.data ``if`  `                           ``random ``is` `not` `None` `else` `-``1``) ` `                            `  `            ``data ``=` `temp.data ` `            ``print``(f"Data``-``{data},  ` `                  ``Random data: {random_data}") ` `            ``temp ``=` `temp.``next` `             `  `        ``return` `"" ` ` `  `    ``# Push method to put data always at  ` `    ``# the head in the linked list. ` `    ``def` `push(``self``, data): ` `         `  `        ``node ``=` `Node(data) ` `        ``node.``next` `=` `self``.head ` `        ``self``.head ``=` `node ` ` `  `    ``# Actual clone method which returns head ` `    ``# reference of cloned linked list. ` `    ``def` `clone(``self``): ` `         `  `        ``# Initialize two references, one  ` `        ``# with original list's head. ` `        ``original ``=` `self``.head ` `        ``clone ``=` `None` ` `  `        ``# Initialize two references, one  ` `        ``# with original list's head. ` `        ``mp ``=` `MyDictionary() ` ` `  `        ``# Traverse the original list and  ` `        ``# make a copy of that ` `        ``# in the clone linked list ` `        ``while` `original ``is` `not` `None``: ` `            ``clone ``=` `Node(original.data) ` `            ``mp.add(original, clone) ` `            ``original ``=` `original.``next` ` `  `        ``# Adjusting the original  ` `        ``# list reference again. ` `        ``original ``=` `self``.head ` ` `  `        ``# Traversal of original list again ` `        ``# to adjust the next and random  ` `        ``# references of clone list using hash map. ` `        ``while` `original ``is` `not` `None``: ` `            ``clone ``=` `mp.get(original) ` `            ``clone.``next` `=` `mp.get(original.``next``) ` `            ``clone.random ``=` `mp.get(original.random) ` `            ``original ``=` `original.``next` `             `  `        ``# Return the head reference of the clone list. ` `        ``return` `LinkedList(``self``.head) ` ` `  `# Driver code ` ` `  `# Pushing data in the linked list. ` `l ``=` `LinkedList(Node(``5``)) ` `l.push(``4``) ` `l.push(``3``) ` `l.push(``2``) ` `l.push(``1``) ` ` `  `# Setting up random references. ` `l.head.random ``=` `l.head.``next``.``next` `l.head.``next``.random ``=`  `l.head.``next``.``next``.``next` `l.head.``next``.``next``.random ``=`  `l.head.``next``.``next``.``next``.``next` `l.head.``next``.``next``.``next``.random ``=`  `(l.head.``next``.``next``.``next``.``next``.``next``) ` `l.head.``next``.``next``.``next``.``next``.random ``=`  `l.head.``next` ` `  `# Making a clone of the  ` `# original linked list. ` `clone ``=` `l.clone() ` ` `  `# Print the original and cloned ` `# linked list.s ` `print``(``"Original linked list"``) ` `print``(l) ` `print``(``"Cloned linked list"``) ` `print``(clone) ` `# This code is contributed by ashwinathappan `

Output:

```Original linked list
Data = 1, Random data = 3
Data = 2, Random data = 4
Data = 3, Random data = 5
Data = 4, Random data = -1
Data = 5, Random data = 2

Data = 1, Random data = 3
Data = 2, Random data = 4
Data = 3, Random data = 5
Data = 4, Random data = -1
Data = 5, Random data = 2```

Time complexity: O(n)
Auxiliary space: O(n)
Please refer complete article on Clone a linked list with next and random pointer | Set 2 for more details!

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