Add integer programming example. Add types for solver algorithms

examples/fsharp/csintegerprogramming.fsx

@@ -0,0 +1,68 @@
+// Copyright 2010-2014 Google
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#I "../../bin"
+#r "Google.OrTools.dll"
+#load "Google.OrTools.FSharp.fsx"
+
+open System
+open Google.OrTools.FSharp
+open Google.OrTools.LinearSolver
+open Google.OrTools.ConstraintSolver
+
+let solver solverType = 
+  let svr = Solver.CreateSolver("IntegerProgramming", solverType.ToString())
+
+  // x1 and x2 are integer non-negative variables.
+  let x1 = svr.MakeIntVar(0.0, Double.PositiveInfinity, "x1")
+  let x2 = svr.MakeIntVar(0.0, Double.PositiveInfinity, "x2")
+
+  // Minimize x1 + 2 * x2.
+  let objective = svr.Objective()
+  objective.SetMinimization()
+  objective.SetCoefficient(x1, 1.0)
+  objective.SetCoefficient(x2, 2.0)
+
+  // 2 * x2 + 3 * x1 >= 17.
+  let ct = svr.MakeConstraint(17.0, Double.PositiveInfinity)
+  ct.SetCoefficient(x1, 3.0)
+  ct.SetCoefficient(x2, 2.0)
+
+  let resultStatus = svr.Solve()
+
+  // Check that the problem has an optimal solution.
+  match resultStatus with
+  | status when status <> Solver.OPTIMAL ->
+      printfn "The problem does not have an optimal solution!"
+      exit 0
+  | _ ->
+      printfn "Problem solved in %i milliseconds" (svr.WallTime())
+
+  // The objective value of the solution.
+  printfn "Optimal objective value = %f" (objective.Value())
+
+  // The value of each variable in the solution.
+  printfn "x1 = %f" (x1.SolutionValue())
+  printfn "x2 = %f" (x2.SolutionValue())
+
+  printfn "Advanced usage:"
+  printfn "Problem solved in %i branch-and-bound nodes" (svr.Nodes())
+
+
+// printfn "---- Integer programming example with %A ----" IntegerProgramming.GLPK
+// solver IntegerProgramming.GLPK
+
+printfn "---- Linear programming example with %A ----" IntegerProgramming.CBC
+solver IntegerProgramming.CBC
+
+// printfn "---- Linear programming example with %A ----" IntegerProgramming.SCIP
+// solver IntegerProgramming.SCIP