given login/logout time of users particular website in form: (userid, login time, logout time). store data, query total number of users logged in , logged out in given time range.
what data structure should use? , how implement it?
the data structure you're looking called interval tree , has binary-search tree format start of interval (login time) values (ordering in bst).
this ds has following time complexities:
- add interval (login-logout): o(logn)
- remove interval: o(logn)
- given interval [start-finish], find overlapping intervals: o(logn)
