Ad Hoc

From Algorithmist

Ad Hoc category contains problems which doesn't need a particular algorithm. It means that you will have to create the algorithm to solve the problem without thinking on Graph Theory, DP, Backtracking or any other algorithms category.

Ad Hoc problems are in general considered easy to solve, in fact, it's the best category for those who are starting, but pay attention, there are also difficult Ad Hoc problems that will need some experience to get solved.