Sort List
A medium-tier problem at 62% community acceptance, tagged with Linked List, Two Pointers, Divide and Conquer. Reported in interviews at ByteDance and 5 others.
Sort List hits your screen during a ByteDance, TikTok, or Palantir OA and you have to sort a linked list. This isn't a simple array sort. The trick is you can't randomly access elements, so the naive approaches fail immediately. Most candidates freeze here because they either try to copy array-sort logic (won't work) or attempt bubble sort on a linked list (way too slow). The pattern is merge sort applied to linked lists, but the implementation has teeth: you need to find the middle using slow/fast pointers, split the list cleanly, and merge two sorted halves. If this problem hits your live assessment and you blank on the merge-sort structure, StealthCoder surfaces a working solution in seconds, invisible to the proctor.
Companies that ask "Sort List"
Sort List is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Made for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoderThe trap is thinking you can use quicksort or heapsort on a linked list cheaply. You can't. Merge sort is the only efficient choice because it works with sequential access and O(log n) space. The real work: use slow and fast pointers to find the midpoint, recursively sort left and right halves, then merge two sorted lists using a two-pointer technique. Most mistakes happen in the merge step (pointer updates, edge cases with one list exhausting before the other) or forgetting to break the list in half (you must set mid.next to null). The acceptance rate is solid at 62 percent, meaning a lot of people solve it, but the implementation is tighter than it looks. Common failures include off-by-one errors in the midpoint search, not handling single-node or two-node base cases, or merging incorrectly. When you hit this during the real OA and the structure doesn't click fast, StealthCoder is the hedge that gets you a clean, working implementation so you can move on.
Pattern tags
You know the problem.
Make sure you actually pass it.
Sort List recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Made for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Sort List interview FAQ
Why can't I just convert the linked list to an array, sort it, and rebuild?+
You technically can, but it defeats the purpose and uses O(n) extra space. The problem expects you to sort in-place on the linked list structure. Interviewers at ByteDance and TikTok specifically test whether you understand that linked lists require different algorithms than arrays. Merge sort shows you know that.
What's the trick to finding the middle of a linked list?+
Slow and fast pointers. Move fast two steps at a time, slow one step. When fast reaches the end, slow is at the midpoint. Don't forget to null out the link after the midpoint so you cleanly split the list. This is the foundation of the entire solution.
How do I merge two sorted linked lists without extra space?+
Create a dummy node pointing to null. Use two pointers to walk both lists. At each step, append the smaller node to the result and advance that pointer. When one list exhausts, attach the entire remainder of the other list. It's O(n) time, O(1) space if you don't count the result list.
Is this still asked at top companies like Palantir and Oracle?+
Yes. Six major companies report asking it, and the 62 percent acceptance rate means it's active in real assessments. It's a medium-difficulty staple because it tests linked list fundamentals and algorithmic thinking in one shot. Expect it.
What's the most common mistake in the implementation?+
Forgetting to set mid.next to null before recursing on the right half. If you don't break the link, the right half still points back into the left half, and your recursion creates an infinite loop or corrupts the list. Check this immediately if your solution hangs.
Want the actual problem statement? View "Sort List" on LeetCode →