workforce3_vb.vb
'版权所有2021，Gurobi优化狗万app足彩，LLC'分配工人转移;每个工人可能会或可能无法在某个日子上使用。如果问题无法解决，请放宽模型'以确定无法满足哪些限制，以及它们需要放松多少。导入系统导入Gurobi类Workforce3_vb共享子Main（）尝试“示例数据”一组天数和工人Dim vipls作为字符串（）= new字符串（）{“mon1”，“tue2”，“wed3”，“thu4”，_“Fri5”，“SAT6”，“Sun7”，“Mon8”，_“Tue9”，“Wed10”，“星期四”，_“Fri12”，“SAT13”，“Sun14”} Dimer Workers作为String（）= newstring（）{amy“，”bob“，”cathy“，”dan“，_”ed“，”fred“，”gu“，”gu“}暗中nshifts作为整数= shifts.length昏暗nworkers作为整数= workers.length'每个Shift昏暗的工作人员需要双（）= new double（）= new double（）{3,2,4,4,5,6，_ 5,2,2,3,4,6，_ 7,5}'每位工作人员都支付给工作一个Shift Dim Pay作为Double（）= new double（）{10,12,10,8,8,9,11}'工人可用性：0如果工人不可用于换档暗淡可用性作为双（，）=新的双（，）{_ {0,1，1,0,1,0,1,0,1，1,1，1,1，1,1}，_ {1,1,0，0,1，1,0,1,0,0,0,1,0,1，0}，_ {0,0,1，1,1，0,1,1,1,1,1，1,1，1，1,1}，_ {0,1,1,0,1，1,0,1，1,1,1,1,1,1,1，1，} _ {1，1，1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1, 1}, _ {1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1}, _ {1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}} ' Model Dim env As New GRBEnv() Dim model As New GRBModel(env) model.ModelName = "assignment" ' Assignment variables: x[w][s] == 1 if worker w is assigned ' to shift s. Since an assignment model always produces integer ' solutions, we use continuous variables and solve as an LP. Dim x As GRBVar(,) = New GRBVar(nWorkers - 1, nShifts - 1) {} For w As Integer = 0 To nWorkers - 1 For s As Integer = 0 To nShifts - 1 x(w, s) = model.AddVar(0, availability(w, s), pay(w), _ GRB.CONTINUOUS, _ Workers(w) & "." & Shifts(s)) Next Next ' The objective is to minimize the total pay costs model.ModelSense = GRB.MINIMIZE ' Constraint: assign exactly shiftRequirements[s] workers ' to each shift s For s As Integer = 0 To nShifts - 1 Dim lhs As GRBLinExpr = 0.0 For w As Integer = 0 To nWorkers - 1 lhs.AddTerm(1.0, x(w, s)) Next model.AddConstr(lhs = shiftRequirements(s), Shifts(s)) Next ' Optimize model.Optimize() Dim status As Integer = model.Status If status = GRB.Status.UNBOUNDED Then Console.WriteLine("The model cannot be solved " & _ "because it is unbounded") Return End If If status = GRB.Status.OPTIMAL Then Console.WriteLine("The optimal objective is " & model.ObjVal) Return End If If (status <> GRB.Status.INF_OR_UNBD) AndAlso _ (status <> GRB.Status.INFEASIBLE) Then Console.WriteLine("Optimization was stopped with status " & _ status) Return End If ' Relax the constraints to make the model feasible Console.WriteLine("The model is infeasible; relaxing the constraints") Dim orignumvars As Integer = model.NumVars model.FeasRelax(0, False, False, True) model.Optimize() status = model.Status If (status = GRB.Status.INF_OR_UNBD) OrElse _ (status = GRB.Status.INFEASIBLE) OrElse _ (status = GRB.Status.UNBOUNDED) Then Console.WriteLine("The relaxed model cannot be solved " & _ "because it is infeasible or unbounded") Return End If If status <> GRB.Status.OPTIMAL Then Console.WriteLine("Optimization was stopped with status " & status) Return End If Console.WriteLine(vbLf & "Slack values:") Dim vars As GRBVar() = model.GetVars() For i As Integer = orignumvars To model.NumVars - 1 Dim sv As GRBVar = vars(i) If sv.X > 1E-06 Then Console.WriteLine(sv.VarName & " = " & sv.X) End If Next ' Dispose of model and environment model.Dispose() env.Dispose() Catch e As GRBException Console.WriteLine("Error code: " + e.ErrorCode & ". " + e.Message) End Try End Sub End Class
