AlgoScope

Skip List

Data structureadvancedLinked Lists

Layered linked lists where higher levels skip ahead, giving expected O(log n) search.

Decision · step 2 of 4Skip List: Search skips along the express lanes
L3L2L1L0headhead✓44✓head✓7✓25✓44✓58✓67✓head✓3✓7✓12✓19✓25✓31✓44✓58✓67✓

Level 3 at the head: the next key on this lane is nothing, the end of the lane. It is not below 44, so drop to level 2 and keep looking from here.

Open in the player →or start at step 2

What you will see

Several rows of nodes; search drops down a level when the next node is too large.

How skip list works →

Cost

searchO(log n) expected
insertO(log n) expected
deleteO(log n) expected
SpaceO(n) expected

Randomized level assignment; bounds are expectednot worst case.

How you work with it here

play it through, step one change at a time, scrub to any step, run it on your own input, try operations in any order.

Screen readers: Each element is an accessibility element with position, value and state; structural changes are announced per step.

Reduced motion: Elements appear at their destination with a crossfade; no travel longer than the element's own size.