[(343, 3), (344, 6), (345, 1), (346, 8), (347, 2)]

# each solution is a list (or tuple rather) like above
hashes_solutions_found = set([hash(sol1), hash(sol2), hash(sol3), ...])

# O(1) check if solution found in this iteration has already been explorend
solution_hash = hash(current_solution)
if solution_hash in hashes_solutions_found:
   return

hashes_solutions_found.add(solution_hash)
value = objective(current_solution)
if value > best_value:
    best_solution, best_value = value, current_solution