insertion deletion comment stack (array or linked ( listo( deletes most recently inserted item queue (array or linked listo( ( deletes least recently inserted item priority queue (ordered arrayo(no( deletes highestpriority item (logndeletes highestpriority item priority queue (heapo(logncomparison of special-purpose structures table shows the big times for stacksqueuesand priority queues these structures don' support searching or traversal special-purpose data structures the special-purpose data structures discussed in this book are the stackthe queueand the priority queue these structuresinstead of supporting database of user-accessible dataare usually used by computer program to aid in carrying out some algorithm we've seen examples of this throughout this booksuch as in "graphs,and "weighted graphs,where stacksqueuesand priority queues are all used in graph algorithms stacksqueuesand priority queues are abstract data types (adtsthat are implemented by more fundamental structure such as an arraylinked listor (in the case of the priority queuea heap these adts present simple interface to the usertypically allowing only insertion and the ability to access or delete only one data item these items are for stacksthe last item inserted for queuesthe first item inserted for priority queuesthe item with the highest priority these adts can be seen as conceptual aids their functionality could be obtained using the underlying structure (such as an arraydirectlybut the reduced interface they offer simplifies many problems these adts can' be conveniently searched for an item by key value or traversed stack stack is used when you want access only to the last data item insertedit' last-infirst-out (lifostructure