This problem is Map coloring Problem.
git clone https://github.com/DimitrisRammos/Graph-Coloring-Project
This program is Work from our first half year in https://www.di.uoa.gr/. This work is in c, and we havn't use data structures( when we wright this code we don't know data structures).
The vocalization of the Project find here.
cd Program
make mapcol
make genmap //for genmap
make run //with example input, if you want change other input file( from Directory Input)