摘要: LetQnbe the random number of comparisons made by quicksort in sortingndistinct keys when we assume that alln! possible orderings are equally likely. Known results concerning moments forQndo not show how rare it is forQnto make large deviations from its mean. Here give a good approximation to probability such deviation and find this quite small. As well as basic quicksort, consider variant which partitioning key chosen median (2t+1) keys.