[PPL-devel] [GIT] ppl/ppl(sparse_matrices): MIP_Problem: use a hint iterator for insertions in working_cost, in process_pending_constraints().

[Marco Poletti]

Module: ppl/ppl
Branch: sparse_matrices
Commit: 343524886abe52d344037a76b186c913eec2f8d4
URL:    http://www.cs.unipr.it/git/gitweb.cgi?p=ppl/ppl.git;a=commit;h=343524886abe52d344037a76b186c913eec2f8d4

Author: Marco Poletti <poletti.marco at gmail.com>
Date:   Wed Sep 15 11:32:27 2010 +0200

MIP_Problem: use a hint iterator for insertions in working_cost, in process_pending_constraints().

---

 src/MIP_Problem.cc |   11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/MIP_Problem.cc b/src/MIP_Problem.cc
index 1b54d00..58c2112 100644
--- a/src/MIP_Problem.cc
+++ b/src/MIP_Problem.cc
@@ -842,12 +842,16 @@ PPL::MIP_Problem::process_pending_constraints() {
   // constraint, will enter the base and will have coefficient -1 in
   // the cost function.
 
+  // This is used as a hint for insertions in working_cost.
+  working_cost_type::iterator cost_itr = working_cost.end();
+
   // First go through nonpending constraints that became unfeasible
   // due to re-merging of split variables.
   for (dimension_type i = 0; i < unfeasible_tableau_rows_size; ++i) {
     tableau[unfeasible_tableau_rows[i]].find_create(artificial_index,
                                                     Coefficient_one());
-    working_cost[artificial_index] = -1;
+    cost_itr = working_cost.find_create(cost_itr, artificial_index);
+    *cost_itr = -1;
     base[unfeasible_tableau_rows[i]] = artificial_index;
     ++artificial_index;
   }
@@ -858,7 +862,8 @@ PPL::MIP_Problem::process_pending_constraints() {
     if (worked_out_row[i])
       continue;
     tableau[i].find_create(artificial_index, Coefficient_one());
-    working_cost[artificial_index] = -1;
+    cost_itr = working_cost.find_create(cost_itr, artificial_index);
+    *cost_itr = -1;
     base[i] = artificial_index;
     ++artificial_index;
   }
@@ -868,7 +873,7 @@ PPL::MIP_Problem::process_pending_constraints() {
   // Set the extra-coefficient of the cost functions to record its sign.
   // This is done to keep track of the possible sign's inversion.
   const dimension_type last_obj_index = working_cost.size() - 1;
-  working_cost[last_obj_index] = 1;
+  working_cost.find_create(cost_itr, last_obj_index, Coefficient_one());
 
   // Express the problem in terms of the variables in base.
   {