Andrei Alexandrescu: > Say at some point there are k available (not taken) slots out of "n". > There is a k/n chance that a random selection finds an unoccupied slot. > The average number of random trials needed to find an unoccupied slot is > proportional to 1/(k/n) = n/k. So the total number of random trials to > span the entire array is quadratic. Multiplying that by 0.9 leaves it > quadratic.
It's like in hashing: if you want to fill 99% of the available space in a hash, then you take ages to find empty slots. But if you fill it only at 75-90%, then on average you need only one or two tries to find an empty slot. So your time is linear, with a small multiplicative constant. When the slots start to get mostly full, you change algorithm, copying the empty slots elsewhere. Bye, bearophile
