Simple and efficient fully-functional succinct trees

The fully-functional succinct tree representation of Navarro and Sadakane (2014) [10] supports a large number of operations in constant time using 2n+o(n) bits. However, the full idea is hard to implement. Only a simplified version with O(lg⁡n) operation time has been implemented and shown to be practical and competitive. We describe a new variant of the original idea that is much simpler to implement and has worst-case time O(lg⁡lg⁡n) for the operations. An implementation based on this version is experimentally shown to be superior to existing implementations.