I've encountered a problem that wants to find any Hamiltonian cycle (it ends where it starts). The graph given has undirected edges (which is **different** than this problem from CSES), and the number of vertices are $$$4 * 10^3$$$. I've been doing some search online for a while now, but eventually none of the solution seems to be better than $$$O(2^n * n)$$$. Do you have any ideas? I'm glad if some (pseudo) codes are provided, if possible. Thank you.