I just uploaded the latest version of libcds. This version contains a bunch of new data structures for representing sequences. In particular, it contains WaveletTreeNoptrsS, a strict version of the original WaveletTreeNoptrs that uses a bit less of memory. The time has been improved for WaveletTreeNoptrs for all operations. We also included a new structure called WaveletMatrix. This one is faster than WaveletTree in many scenarios, and can achieve similar compression (sometimes you need to use MapperRev, a new Mapper) to achieve good compression.