Everything is in place to insert the real way. Today the public Insert picks a tower height from the seeded generator instead of taking one by hand, so the list balances itself while staying perfectly reproducible.
Add a public Insert that draws a random height from the list's generator, then splices the node in.
This is where the pieces meet. The insert helper from chapter one already knows how
to splice a node of a given height into its sorted place and raise the list level;
all Insert adds is drawing that height from the list’s own randomLevel instead of
receiving it as an argument. The result is a list that assigns heights the way a real
skip list does - mostly short towers, occasionally a tall one - so its express lanes
stay balanced no matter what order the keys arrive in.
Because the generator is seeded, the “random” heights are still exactly predictable. Starting from seed 1, the first two inserts draw height 1 and the third draws height 3, so inserting 5, 3, then 8 makes node 8 a height-3 tower that lifts the list to level 3. Same seed, same insertions, same structure, every single time - which is what makes the coming lessons on duplicates, deletion, and rank testable to the exact pointer.
// The public entry point: pick a height, then reuse the splice from before.func (s *SkipList) Insert(key, val int) {h := s.randomLevel()s.insert(key, val, h)}