Additional notes
Random binary search trees have been studied extensively. DevroyeL. Devroye. Applications of the theory of records in the study of random trees. Acta Informatica, 26(1):123–130, 1988. gives a proof of the lemmaThe lemma is about the length of search path in a binary search tree. and related results. There are much stronger
results in the literature as well, the most impressive of which is due to ReedB. Reed. The height of a random binary search tree. Journal of the ACM, 50(3):306–332, 2003., who shows that the expected height of a random binary search
tree is
αlnn−βlnlnn+O(1)
where a≈4.31107 is the unique solution on the interval [2,∞) of the equation αln((2e/ ...