Identify

• to reverse the links between a set of nodes of a linked list when there is a constraint to do it without using extra memory

Motive

• there is a constraint to do it without using extra memory

Steps

• reverse one node at a time starting with one variable (current) pointing to the head of the linked list, and one variable (previous) will point to the previous node that you have processed, initially previous will point to null
• in a lock-step manner, you will reverse the current node by pointing it to the previous before moving on to the next node, also, you will update the variable “previous” to always point to the previous node that you have processed

Complexity

Time O(n)

Space O(1)

Common Problems

• [ ] Reverse a LinkedList (easy) Leetcode
• [ ] Reverse a Sub-list (medium) Leetcode
• [ ] Reverse every K-element Sub-list (medium) Leetcode
• [ ] Reverse alternating K-element Sub-list (medium) Geeksforgeeks
• [ ] Rotate a LinkedList (medium) Leetcode
• [ ] Detect Cycle in a Linked List https://leetcode.com/problems/linked-list-cycle/
• [ ] Merge Two Sorted Lists https://leetcode.com/problems/merge-two-sorted-lists/
• [ ] Merge K Sorted Lists https://leetcode.com/problems/merge-k-sorted-lists/