Do most of you guys use templates for coding things such as Segment Trees that are hard to code? If so, did you write them yourself or are there any good implementations or templates available online? (Is this even allowed?)

Also, what other data structures are useful to have templates for?

Topcoder SRM 647 will be held tomorrow (Saturday) at 12:00 Noon EST; details here. Discuss the problems here after the contest!

Topcoder SRM 645 will be held tomorrow (Monday) at 11:00 AM EST (see below for your time zone). Official announcement here.

So, see here for the time of Monday's round. This thread can be used for pre/post-contest discussion.