Given a singly linked list of integers, the task is to sort it using iterative merge sort.
Merge Sort is often preferred for sorting a linked list. It is discussed here. However, the method discussed above uses Stack for storing recursion calls. This may consume a lot of memory if the linked list to be sorted is too large. Hence, a purely iterative method for Merge Sort with no recursive calls is discussed in this post.
We use bottom-up approach of Merge Sort in this post. We know that Merge Sort first merges two items, then 4 items and so on. The idea is to use an integer variable to store the gap to find the midpoint around which the linked list needs to be sorted. So the problem reduces to merging two sorted Linked List which is discussed here. However, we do not use an additional list to keep the merged list. Instead we merge the lists within itself. The gap is incremented exponentially by 2 in each iteration and the process is repeated.
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Time Complexity : O(n Log n)
Auxiliary Space : O(1)
- Merge Sort for Doubly Linked List
- Iterative Merge Sort
- C Program for Iterative Merge Sort
- Python Program for Iterative Merge Sort
- Java Program for Iterative Merge Sort
- Why Quick Sort preferred for Arrays and Merge Sort for Linked Lists?
- Merge a linked list into another linked list at alternate positions
- Merge Sort for Linked Lists
- Union and Intersection of two linked lists | Set-2 (Using Merge Sort)
- Merge two sorted linked list without duplicates
- Construct a linked list from 2D matrix (Iterative Approach)
- Check if linked list is sorted (Iterative and Recursive)
- Search an element in a Linked List (Iterative and Recursive)
- Find Length of a Linked List (Iterative and Recursive)
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