From 39d4b467ac4333f7abcbbd45fe521864dfaca29c Mon Sep 17 00:00:00 2001
From: Corentin Le Molgat <corentinl@google.com>
Date: Wed, 17 Jul 2024 11:29:47 +0200
Subject: [PATCH] algorithms: std::vector -> absl::Span

---
 ortools/algorithms/find_graph_symmetries_test.cc | 9 ++++-----
 ortools/algorithms/hungarian.cc                  | 2 +-
 ortools/algorithms/hungarian.h                   | 2 +-
 3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/ortools/algorithms/find_graph_symmetries_test.cc b/ortools/algorithms/find_graph_symmetries_test.cc
index 3789c6927c..8350297924 100644
--- a/ortools/algorithms/find_graph_symmetries_test.cc
+++ b/ortools/algorithms/find_graph_symmetries_test.cc
@@ -262,8 +262,8 @@ class FindSymmetriesTest : public ::testing::Test {
     return dense_perm;
   }
 
-  std::vector<int> ComposePermutations(const std::vector<int>& p1,
-                                       const std::vector<int>& p2) {
+  std::vector<int> ComposePermutations(absl::Span<const int> p1,
+                                       absl::Span<const int> p2) {
     CHECK_EQ(p1.size(), p2.size());
     std::vector<int> composed(p1.size(), -1);
     for (int i = 0; i < p1.size(); ++i) composed[i] = p1[p2[i]];
@@ -274,7 +274,7 @@ class FindSymmetriesTest : public ::testing::Test {
   // with some basic, non-through EXPECT(..) that check that each generator
   // does make the group grow.
   int ComputePermutationGroupSizeAndVerifyBasicIrreductibility(
-      const std::vector<std::unique_ptr<SparsePermutation>>& generators) {
+      absl::Span<const std::unique_ptr<SparsePermutation>> generators) {
     if (generators.empty()) return 1;  // The identity.
     const int num_nodes = generators[0]->Size();
     // The group only contains the identity at first.
@@ -697,8 +697,7 @@ void AddReverseArcsAndFinalize(Graph* graph) {
   graph->Build();
 }
 
-void SetGraphEdges(const std::vector<std::pair<int, int>>& edges,
-                   Graph* graph) {
+void SetGraphEdges(absl::Span<const std::pair<int, int>> edges, Graph* graph) {
   DCHECK_EQ(graph->num_arcs(), 0);
   for (const auto [from, to] : edges) graph->AddArc(from, to);
   AddReverseArcsAndFinalize(graph);
diff --git a/ortools/algorithms/hungarian.cc b/ortools/algorithms/hungarian.cc
index 5dbf9d4186..13ce012024 100644
--- a/ortools/algorithms/hungarian.cc
+++ b/ortools/algorithms/hungarian.cc
@@ -653,7 +653,7 @@ bool InputContainsNan(absl::Span<const std::vector<double>> input) {
 }
 
 void MinimizeLinearAssignment(
-    const std::vector<std::vector<double>>& cost,
+    absl::Span<const std::vector<double>> cost,
     absl::flat_hash_map<int, int>* direct_assignment,
     absl::flat_hash_map<int, int>* reverse_assignment) {
   if (InputContainsNan(cost)) {
diff --git a/ortools/algorithms/hungarian.h b/ortools/algorithms/hungarian.h
index 19c32fc187..7f24103a3f 100644
--- a/ortools/algorithms/hungarian.h
+++ b/ortools/algorithms/hungarian.h
@@ -47,7 +47,7 @@ namespace operations_research {
 
 // See IMPORTANT NOTE at the top of the file.
 void MinimizeLinearAssignment(
-    const std::vector<std::vector<double>>& cost,
+    absl::Span<const std::vector<double>> cost,
     absl::flat_hash_map<int, int>* direct_assignment,
     absl::flat_hash_map<int, int>* reverse_assignment);