cmake build not working

[Alejandro Fernández Suárez]

Hi, I found this repo interesting to contribute with some of my data structures and C++ implementations of algorithms, but I can only build the demos using the UNIX makefile. For some reason, the cmake project
setup is broken and it fails after running the Makefile generated by cmake.

I think it's because the include folders are not set accordingly. I'll try to fix it myself before adding my code. If I succeed, I'll send you my pull request. Thanks for the great work!

[xtaci]

I tested Makefile on my Mac only, the existing cmake file is contributed by other people long ago.
looking forward to your pull request. thanks.