Fisher and Jaikumar [1981] presented a clustering heuristic for the CVRP where the number
of vehicles is fixed to K. In their approach a number of seed customers are selected initially and for each remaining customer i, a heuristic cost dik of routing customer i with seed customer k is computed. A generalized assignment problem is then solved, using dik in the objective. This produces K clusters that each satisfies the capacity constraint. Each cluster is turned into a route by solving a TSP to optimality