The partitioning problem is relevant in many fields and in particular it frequently arises in computer system design, in the allocation of computer information to blocks of storage, and in the assignment of tasks in a multicomputer system. In this paper an efficient algorithm for the partitioning of a new class of graphs, called «basic graphs» with size contraints, is introduced. The algorithm finds the optimal solution in a pseudo polynomial time, as a function of the nodes number and of the size constraints. [ABSTRACT FROM AUTHOR]