from __future__ import print_function# Import Python wrapper for or-tools constraint solver.
from ortools.constraint_solver import pywrapcpdef main():# Create the solver.solver = pywrapcp.Solver('jobshop')machines_count = 3jobs_count = 3all_machines = range(0, machines_count)all_jobs = range(0, jobs_count)# Define data.machines = [[0, 1, 2],[0, 2, 1],[1, 2]]processing_times = [[3, 2, 2],[2, 1, 4],[4, 3]]# Computes horizon.horizon = 0for i in all_jobs:horizon += sum(processing_times[i])# Creates jobs.all_tasks = {}for i in all_jobs:for j in range(0, len(machines[i])):all_tasks[(i, j)] = solver.FixedDurationIntervalVar(0,horizon,processing_times[i][j],False,'Job_%i_%i' % (i, j))# Creates sequence variables and add disjunctive constraints.all_sequences = []all_machines_jobs = []for i in all_machines:machines_jobs = []for j in all_jobs:for k in range(0, len(machines[j])):if machines[j][k] == i:machines_jobs.append(all_tasks[(j, k)])disj = solver.DisjunctiveConstraint(machines_jobs, 'machine %i' % i)all_sequences.append(disj.SequenceVar())solver.Add(disj)# Add conjunctive contraints.for i in all_jobs:for j in range(0, len(machines[i]) - 1):solver.Add(all_tasks[(i, j + 1)].StartsAfterEnd(all_tasks[(i, j)]))# Set the objective.obj_var = solver.Max([all_tasks[(i, len(machines[i])-1)].EndExpr()for i in all_jobs])objective_monitor = solver.Minimize(obj_var, 1)# Create search phases.sequence_phase = solver.Phase([all_sequences[i] for i in all_machines],solver.SEQUENCE_DEFAULT)vars_phase = solver.Phase([obj_var],solver.CHOOSE_FIRST_UNBOUND,solver.ASSIGN_MIN_VALUE)main_phase = solver.Compose([sequence_phase, vars_phase])# Create the solution collector.collector = solver.LastSolutionCollector()# Add the interesting variables to the SolutionCollector.
  collector.Add(all_sequences)collector.AddObjective(obj_var)for i in all_machines:sequence = all_sequences[i];sequence_count = sequence.Size();for j in range(0, sequence_count):t = sequence.Interval(j)collector.Add(t.StartExpr().Var())collector.Add(t.EndExpr().Var())# Solve the problem.disp_col_width = 10if solver.Solve(main_phase, [objective_monitor, collector]):print("\nOptimal Schedule Length:", collector.ObjectiveValue(0), "\n")sol_line = ""sol_line_tasks = ""print("Optimal Schedule", "\n")for i in all_machines:seq = all_sequences[i]sol_line += "Machine " + str(i) + ": "sol_line_tasks += "Machine " + str(i) + ": "sequence = collector.ForwardSequence(0, seq)seq_size = len(sequence)for j in range(0, seq_size):t = seq.Interval(sequence[j]);# Add spaces to output to align columns.sol_line_tasks +=  t.Name() + " " * (disp_col_width - len(t.Name()))for j in range(0, seq_size):t = seq.Interval(sequence[j]);sol_tmp = "[" + str(collector.Value(0, t.StartExpr().Var())) + ","sol_tmp += str(collector.Value(0, t.EndExpr().Var())) + "] "# Add spaces to output to align columns.sol_line += sol_tmp + " " * (disp_col_width - len(sol_tmp))sol_line += "\n"sol_line_tasks += "\n"print(sol_line_tasks)print("Time Intervals for Tasks\n")print(sol_line)if __name__ == '__main__':main()