Problem Complexity for the task ? Data Structure Monitor VISA Credit transactions. Get the largest 10 transactions every Approximately 1500 transactions per second second. card Model student social interactions. Search friends group of a given student An undo list for a text editor. Retrieve the previous change. A job scheduler which processes the Get the highest priority job documents according to their priority. Document statistics Count usage of words in a given document Live concerts and events ticket selling system List events between time a and b