This practice workspace is built for desktop. Open it on a larger screen to start solving.
Swap Nodes in Pairs
Given a linked list, swap every two adjacent nodes and return the new head. You must solve the problem without modifying the values in the list's nodes — only nodes themselves may be changed.
Input/output convention for this exercise: the list is passed as an array of values; return the result as an array of values. The starter provides ListNode, arrayToList, and listToArray to convert between forms.
A dummy head node makes the iterative solution straightforward: at each step, splice out a pair and re-link it in reverse. Recursion is also clean — swap the first two, then recurse on the rest.
Examples
Constraints
- 0 <= values.length <= 100
- 0 <= values[i] <= 100
Preview Mode
This is a read-only preview of DSAMind's AI coaching. Sign up to get custom feedback on your own solution.
Your approach
- Pattern:Linked List
- Time:O(N)
- Space:O(1)
Complete approach — pattern and complexity both named.
Coach
What you got right
You correctly matched the sorted input requirement and implemented a linear-time scan using two pointers.
Where it diverged
No divergence detected. The code correctly aligns with the stated approach.
Next attempt: focus on
Try solving related sliding window problems to build familiarity with two-pointer variants.
Signals
No signals fired — clean run, you stayed in flow.