Put remove operations skip list with entries and height

416	Chapter 9. Maps and Dictionaries
	Remaval in a Skip List



	Before we give this analysis, however, there are some minor improvements to
	the skip list data structure we would like to discuss. First, we don't actually need




	fashion, thus saving space for "up" and "prev" references. We explore the details
	of this optimization in Exercise C-9.10. Neither of these optimizations improve




	The positions visited after the search for ttie position of So holding the entry are
	highlighted in blue. The positions removed are drawn with dasbed lines.

		417


	possible courses of action we can take, both of which have their merits.
	One possibility is to restriet the top level, h, to be kept at some fixed value that



	long as heads keeps getting returned from the random number generator. This is the approach taken in Algorithm Skiplnsert of Code Fragment 9.11. As we show
	in the analysis of skip lists, the probability that an insertion will go to a level that is
	more than O(logn) is very low, so this design choice should also work.





	map. In terms of worst-case performance, however, skip lists ale not a superior
	data structure. In fact, if we don't officially prevent an insection from continuing




	However, this event has very low probability. Iudging from this worst case, we
	might conclude that the skip list structure is strictly inferior to the other map imple-