Given a linked list having two pointers in each node. The first one points to the next node of the list, however the other pointer is random and can point to any node of the list. Write a program that clones the given list in O(1) space, i.e., without any extra space.
Input : Head of the below linked list Output : A new linked listidentical to the original list.
In this post we’ll be implementing an algorithm that’d require no additional space as discussed in Set-1.
Below is the Algorithm:
- Create the copy of node 1 and insert it between node 1 & node 2 in original Linked List, create the copy of 2 and insert it between 2 & 3.. Continue in this fashion, add the copy of N afte the Nth node
- Now copy the random link in this fashion
original->next->random= original->random->next; /*TRAVERSE TWO NODES*/
This works because original->next is nothing but copy of original and Original->random->next is nothing but copy of random.
- Now restore the original and copy linked lists in this fashion in a single loop.
original->next = original->next->next; copy->next = copy->next->next;
- Ensure that original->next is NULL and return the cloned list
Below is the implementation.
Original list : Data = 1, Random = 3 Data = 2, Random = 1 Data = 3, Random = 5 Data = 4, Random = 5 Data = 5, Random = 2 Cloned list : Data = 1, Random = 3 Data = 2, Random = 1 Data = 3, Random = 5 Data = 4, Random = 5 Data = 5, Random = 2
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