From b948cc5c1e8fee9f44e4019c4c76ee5db7b9a59c Mon Sep 17 00:00:00 2001
From: Andrew Teirney <andrew@teirney.net>
Date: Mon, 20 Jan 2020 21:08:03 +1300
Subject: [PATCH 1/2] feat: add support for adding extra cost variables to the
 cost function

---
 ortools/constraint_solver/routing.cc |  3 +++
 ortools/constraint_solver/routing.h  | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/ortools/constraint_solver/routing.cc b/ortools/constraint_solver/routing.cc
index 6a71e578a32..2a3eab0232a 100644
--- a/ortools/constraint_solver/routing.cc
+++ b/ortools/constraint_solver/routing.cc
@@ -2147,6 +2147,9 @@ void RoutingModel::CloseModelWithParameters(
   for (int i = 0; i < same_vehicle_costs_.size(); ++i) {
     cost_elements.push_back(CreateSameVehicleCost(i));
   }
+  // Add in any extra cost elements
+  cost_elements.insert(cost_elements.end(), extra_costs_.begin(), extra_costs_.end());
+
   cost_ = solver_->MakeSum(cost_elements)->Var();
   cost_->set_name("Cost");
 
diff --git a/ortools/constraint_solver/routing.h b/ortools/constraint_solver/routing.h
index bfa8e9c71ab..21857acee48 100644
--- a/ortools/constraint_solver/routing.h
+++ b/ortools/constraint_solver/routing.h
@@ -1072,6 +1072,15 @@ class RoutingModel {
     }
     extra_filters_.push_back(filter);
   }
+  // Adds a custom extra cost to the list of cost elements that make up the
+  // objective value
+  void AddExtraCost(IntVar* intVar) {
+    CHECK(intVar != nullptr);
+    if (closed_) {
+      LOG(WARNING) << "Model is closed, cost addition will be ignored.";
+    }
+    extra_costs_.push_back(intVar);
+  }
 
   /// Model inspection.
   /// Returns the variable index of the starting node of a vehicle route.
@@ -1679,6 +1688,7 @@ class RoutingModel {
   std::vector<LocalSearchFilter*> filters_;
   std::vector<LocalSearchFilter*> feasibility_filters_;
   std::vector<LocalSearchFilter*> extra_filters_;
+  std::vector<IntVar*> extra_costs_;
 #ifndef SWIG
   std::vector<std::pair<IntVar*, int64>> finalizer_variable_cost_pairs_;
   std::vector<std::pair<IntVar*, int64>> finalizer_variable_target_pairs_;

From c8b6d5f3f94d4d620b5df045fab35837ce73e746 Mon Sep 17 00:00:00 2001
From: Andrew Teirney <andrew@teirney.net>
Date: Mon, 20 Jan 2020 21:12:45 +1300
Subject: [PATCH 2/2] feat: rename the AddExtraCost method in the Java SWIG
 bindings to be lowerCamelCase

---
 ortools/constraint_solver/java/routing.i | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ortools/constraint_solver/java/routing.i b/ortools/constraint_solver/java/routing.i
index 76d7c9ceaa2..3b8b6254d0a 100644
--- a/ortools/constraint_solver/java/routing.i
+++ b/ortools/constraint_solver/java/routing.i
@@ -145,6 +145,7 @@ import java.util.function.LongUnaryOperator;
 %rename (compactAssignment) RoutingModel::CompactAssignment;
 %rename (computeLowerBound) RoutingModel::ComputeLowerBound;
 %rename (costVar) RoutingModel::CostVar;
+%rename (addExtraCost) RoutingModel::AddExtraCost;
 %rename (costsAreHomogeneousAcrossVehicles) RoutingModel::CostsAreHomogeneousAcrossVehicles;
 %rename (debugOutputAssignment) RoutingModel::DebugOutputAssignment;
 %rename (end) RoutingModel::End;