Branch and Bound algorithm (B&B) is an exact method for finding an optimal solution to an NP- hard problem. It is an enumerative technique that can be applied to a wide class of combinatorial optimisation problems. To describe the B&B algorithm, consider problem 1|ET,. This problem is NP-hard, i.e., it is unlikely that there can be developed a polynomial-time algorithm for finding an optimal schedule. The input data for the instance with n=4 jobs is given by the following table: Jobs 1 2 3 4 Pj 12 8 15 9 16 26 25 27