This simple C source code is written in dev-C++ platform, (OS- Win 7). Here, in a given random simple symmetric graph, whether there a Hamiltonian circuit exists or not, is being checked. This is based on the formula: If 2e >= [ (n^2) - 3n + 6 ], then there hamiltonian circuit exits, else not. e & n are the number of edges & vertices respectively here.