diff --git a/examples/robot_pose_mle.cc b/examples/robot_pose_mle.cc
index 7dd981d..728c9c2 100644
--- a/examples/robot_pose_mle.cc
+++ b/examples/robot_pose_mle.cc
@@ -125,6 +125,7 @@
 // will be computed by a DynamicAutoDiffCostFunction since the number of
 // odometry observations will only be known at run time.
 
+#include <algorithm>
 #include <cmath>
 #include <cstdio>
 #include <random>
diff --git a/internal/ceres/block_jacobian_writer.cc b/internal/ceres/block_jacobian_writer.cc
index 4f1834a..544e913 100644
--- a/internal/ceres/block_jacobian_writer.cc
+++ b/internal/ceres/block_jacobian_writer.cc
@@ -32,6 +32,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <vector>
 
 #include "ceres/block_evaluate_preparer.h"
 #include "ceres/block_sparse_matrix.h"
diff --git a/internal/ceres/callbacks.cc b/internal/ceres/callbacks.cc
index 79f35e0..1fab385 100644
--- a/internal/ceres/callbacks.cc
+++ b/internal/ceres/callbacks.cc
@@ -32,6 +32,7 @@
 
 #include <algorithm>
 #include <iostream>  // NO LINT
+#include <string>
 
 #include "ceres/program.h"
 #include "ceres/stringprintf.h"
diff --git a/internal/ceres/canonical_views_clustering.cc b/internal/ceres/canonical_views_clustering.cc
index aec2cb1..2a2810f 100644
--- a/internal/ceres/canonical_views_clustering.cc
+++ b/internal/ceres/canonical_views_clustering.cc
@@ -33,6 +33,7 @@
 
 #include <unordered_map>
 #include <unordered_set>
+#include <vector>
 
 #include "ceres/graph.h"
 #include "ceres/internal/export.h"
@@ -62,7 +63,7 @@
  private:
   void FindValidViews(IntSet* valid_views) const;
   double ComputeClusteringQualityDifference(
-      const int candidate, const std::vector<int>& centers) const;
+      int candidate, const std::vector<int>& centers) const;
   void UpdateCanonicalViewAssignments(const int canonical_view);
   void ComputeClusterMembership(const std::vector<int>& centers,
                                 IntMap* membership) const;
diff --git a/internal/ceres/coordinate_descent_minimizer.cc b/internal/ceres/coordinate_descent_minimizer.cc
index 8087a58..3abbefb 100644
--- a/internal/ceres/coordinate_descent_minimizer.cc
+++ b/internal/ceres/coordinate_descent_minimizer.cc
@@ -32,8 +32,11 @@
 
 #include <algorithm>
 #include <iterator>
+#include <map>
 #include <memory>
 #include <numeric>
+#include <set>
+#include <string>
 #include <vector>
 
 #include "ceres/evaluator.h"
@@ -69,6 +72,9 @@
 
   // Serialize the OrderedGroups into a vector of parameter block
   // offsets for parallel access.
+
+  // TODO(sameeragarwal): Investigate if parameter_block_index should be an
+  // ordered or an unordered container.
   std::map<ParameterBlock*, int> parameter_block_index;
   std::map<int, std::set<double*>> group_to_elements =
       ordering.group_to_elements();
@@ -234,6 +240,8 @@
     const Program& program,
     const ParameterBlockOrdering& ordering,
     std::string* message) {
+  // TODO(sameeragarwal): Investigate if this should be an ordered or an
+  // unordered group.
   const std::map<int, std::set<double*>>& group_to_elements =
       ordering.group_to_elements();
 
diff --git a/internal/ceres/cost_function_to_functor_test.cc b/internal/ceres/cost_function_to_functor_test.cc
index 0d1e901..c02e0e4 100644
--- a/internal/ceres/cost_function_to_functor_test.cc
+++ b/internal/ceres/cost_function_to_functor_test.cc
@@ -32,6 +32,7 @@
 
 #include <cstdint>
 #include <memory>
+#include <vector>
 
 #include "ceres/autodiff_cost_function.h"
 #include "ceres/dynamic_autodiff_cost_function.h"
diff --git a/internal/ceres/covariance_test.cc b/internal/ceres/covariance_test.cc
index 7d477a7..8455721 100644
--- a/internal/ceres/covariance_test.cc
+++ b/internal/ceres/covariance_test.cc
@@ -36,6 +36,7 @@
 #include <map>
 #include <memory>
 #include <utility>
+#include <vector>
 
 #include "ceres/autodiff_cost_function.h"
 #include "ceres/compressed_row_sparse_matrix.h"
@@ -404,6 +405,8 @@
 
 class CovarianceTest : public ::testing::Test {
  protected:
+  // TODO(sameeragarwal): Investigate if this should be an ordered or an
+  // unordered map.
   using BoundsMap = std::map<const double*, std::pair<int, int>>;
 
   void SetUp() override {
diff --git a/internal/ceres/dynamic_autodiff_cost_function_test.cc b/internal/ceres/dynamic_autodiff_cost_function_test.cc
index d4800c2..7b2239c 100644
--- a/internal/ceres/dynamic_autodiff_cost_function_test.cc
+++ b/internal/ceres/dynamic_autodiff_cost_function_test.cc
@@ -34,6 +34,7 @@
 
 #include <cstddef>
 #include <memory>
+#include <vector>
 
 #include "gtest/gtest.h"
 
diff --git a/internal/ceres/dynamic_compressed_row_jacobian_writer.cc b/internal/ceres/dynamic_compressed_row_jacobian_writer.cc
index 78d1875..f84f44a 100644
--- a/internal/ceres/dynamic_compressed_row_jacobian_writer.cc
+++ b/internal/ceres/dynamic_compressed_row_jacobian_writer.cc
@@ -31,6 +31,8 @@
 #include "ceres/dynamic_compressed_row_jacobian_writer.h"
 
 #include <memory>
+#include <utility>
+#include <vector>
 
 #include "ceres/casts.h"
 #include "ceres/compressed_row_jacobian_writer.h"
diff --git a/internal/ceres/dynamic_compressed_row_sparse_matrix_test.cc b/internal/ceres/dynamic_compressed_row_sparse_matrix_test.cc
index c32233c..b4f7cd9 100644
--- a/internal/ceres/dynamic_compressed_row_sparse_matrix_test.cc
+++ b/internal/ceres/dynamic_compressed_row_sparse_matrix_test.cc
@@ -31,6 +31,7 @@
 #include "ceres/dynamic_compressed_row_sparse_matrix.h"
 
 #include <memory>
+#include <vector>
 
 #include "ceres/casts.h"
 #include "ceres/compressed_row_sparse_matrix.h"
diff --git a/internal/ceres/dynamic_numeric_diff_cost_function_test.cc b/internal/ceres/dynamic_numeric_diff_cost_function_test.cc
index 0dae837..f9ae2ee 100644
--- a/internal/ceres/dynamic_numeric_diff_cost_function_test.cc
+++ b/internal/ceres/dynamic_numeric_diff_cost_function_test.cc
@@ -33,6 +33,7 @@
 
 #include <cstddef>
 #include <memory>
+#include <vector>
 
 #include "gtest/gtest.h"
 
diff --git a/internal/ceres/evaluator_test.cc b/internal/ceres/evaluator_test.cc
index d9a1b21..34ec78c 100644
--- a/internal/ceres/evaluator_test.cc
+++ b/internal/ceres/evaluator_test.cc
@@ -34,6 +34,8 @@
 #include "ceres/evaluator.h"
 
 #include <memory>
+#include <string>
+#include <vector>
 
 #include "ceres/casts.h"
 #include "ceres/cost_function.h"
diff --git a/internal/ceres/file.cc b/internal/ceres/file.cc
index 5874cd7..a5338d5 100644
--- a/internal/ceres/file.cc
+++ b/internal/ceres/file.cc
@@ -33,6 +33,7 @@
 #include "ceres/file.h"
 
 #include <cstdio>
+#include <string>
 
 #include "glog/logging.h"
 
diff --git a/internal/ceres/gradient_problem_solver.cc b/internal/ceres/gradient_problem_solver.cc
index 3438409..e4c96aa 100644
--- a/internal/ceres/gradient_problem_solver.cc
+++ b/internal/ceres/gradient_problem_solver.cc
@@ -30,6 +30,7 @@
 
 #include "ceres/gradient_problem_solver.h"
 
+#include <map>
 #include <memory>
 #include <string>
 
diff --git a/internal/ceres/graph_algorithms_test.cc b/internal/ceres/graph_algorithms_test.cc
index ac56497..ddd6914 100644
--- a/internal/ceres/graph_algorithms_test.cc
+++ b/internal/ceres/graph_algorithms_test.cc
@@ -33,6 +33,7 @@
 #include <algorithm>
 #include <memory>
 #include <unordered_set>
+#include <vector>
 
 #include "ceres/graph.h"
 #include "ceres/internal/export.h"
diff --git a/internal/ceres/line_search.cc b/internal/ceres/line_search.cc
index 2b6fe4d..036c739 100644
--- a/internal/ceres/line_search.cc
+++ b/internal/ceres/line_search.cc
@@ -33,8 +33,11 @@
 #include <algorithm>
 #include <cmath>
 #include <iomanip>
-#include <iostream>  // NOLINT
+#include <map>
 #include <memory>
+#include <ostream>  // NOLINT
+#include <string>
+#include <vector>
 
 #include "ceres/evaluator.h"
 #include "ceres/function_sample.h"
diff --git a/internal/ceres/parameter_block_ordering.cc b/internal/ceres/parameter_block_ordering.cc
index 669d5fd..753f9c9 100644
--- a/internal/ceres/parameter_block_ordering.cc
+++ b/internal/ceres/parameter_block_ordering.cc
@@ -30,8 +30,11 @@
 
 #include "ceres/parameter_block_ordering.h"
 
+#include <map>
 #include <memory>
+#include <set>
 #include <unordered_set>
+#include <vector>
 
 #include "ceres/graph.h"
 #include "ceres/graph_algorithms.h"
@@ -164,6 +167,8 @@
     return;
   }
 
+  // TODO(sameeragarwal): Investigate if this should be a set or an
+  // unordered_set.
   const std::map<int, std::set<double*>>& group_to_elements =
       ordering->group_to_elements();
   for (const auto& g_t_e : group_to_elements) {
diff --git a/internal/ceres/polynomial_test.cc b/internal/ceres/polynomial_test.cc
index ea701b0..c214f0f 100644
--- a/internal/ceres/polynomial_test.cc
+++ b/internal/ceres/polynomial_test.cc
@@ -35,6 +35,7 @@
 #include <cmath>
 #include <cstddef>
 #include <limits>
+#include <vector>
 
 #include "ceres/function_sample.h"
 #include "ceres/test_util.h"
diff --git a/internal/ceres/problem_test.cc b/internal/ceres/problem_test.cc
index a3f26dd..70a8469 100644
--- a/internal/ceres/problem_test.cc
+++ b/internal/ceres/problem_test.cc
@@ -32,6 +32,8 @@
 #include "ceres/problem.h"
 
 #include <memory>
+#include <string>
+#include <vector>
 
 #include "ceres/autodiff_cost_function.h"
 #include "ceres/casts.h"
diff --git a/internal/ceres/reorder_program.cc b/internal/ceres/reorder_program.cc
index ad9d0d2..d623b96 100644
--- a/internal/ceres/reorder_program.cc
+++ b/internal/ceres/reorder_program.cc
@@ -31,8 +31,11 @@
 #include "ceres/reorder_program.h"
 
 #include <algorithm>
+#include <map>
 #include <memory>
 #include <numeric>
+#include <set>
+#include <string>
 #include <vector>
 
 #include "Eigen/SparseCore"
@@ -227,6 +230,8 @@
       program->mutable_parameter_blocks();
   parameter_blocks->clear();
 
+  // TODO(sameeragarwal): Investigate whether this should be a set or an
+  // unordered_set.
   const std::map<int, std::set<double*>>& groups = ordering.group_to_elements();
   for (const auto& p : groups) {
     const std::set<double*>& group = p.second;
@@ -484,6 +489,9 @@
     // group.
 
     // Verify that the first elimination group is an independent set.
+
+    // TODO(sameeragarwal): Investigate if this should be a set or an
+    // unordered_set.
     const std::set<double*>& first_elimination_group =
         parameter_block_ordering->group_to_elements().begin()->second;
     if (!program->IsParameterBlockSetIndependent(first_elimination_group)) {
diff --git a/internal/ceres/reorder_program_test.cc b/internal/ceres/reorder_program_test.cc
index 88f84b6..8cbcf77 100644
--- a/internal/ceres/reorder_program_test.cc
+++ b/internal/ceres/reorder_program_test.cc
@@ -31,6 +31,7 @@
 #include "ceres/reorder_program.h"
 
 #include <random>
+#include <vector>
 
 #include "ceres/internal/config.h"
 #include "ceres/parameter_block.h"
diff --git a/internal/ceres/residual_block_test.cc b/internal/ceres/residual_block_test.cc
index 0a84248..6845d56 100644
--- a/internal/ceres/residual_block_test.cc
+++ b/internal/ceres/residual_block_test.cc
@@ -31,6 +31,8 @@
 #include "ceres/residual_block.h"
 
 #include <cstdint>
+#include <string>
+#include <vector>
 
 #include "ceres/internal/eigen.h"
 #include "ceres/manifold.h"
diff --git a/internal/ceres/rotation_test.cc b/internal/ceres/rotation_test.cc
index 3191ec5..c5a2016 100644
--- a/internal/ceres/rotation_test.cc
+++ b/internal/ceres/rotation_test.cc
@@ -30,6 +30,7 @@
 
 #include "ceres/rotation.h"
 
+#include <algorithm>
 #include <array>
 #include <cmath>
 #include <limits>
diff --git a/internal/ceres/solver.cc b/internal/ceres/solver.cc
index fa07055..688d027 100644
--- a/internal/ceres/solver.cc
+++ b/internal/ceres/solver.cc
@@ -32,6 +32,7 @@
 #include "ceres/solver.h"
 
 #include <algorithm>
+#include <map>
 #include <memory>
 #include <sstream>  // NOLINT
 #include <string>
diff --git a/internal/ceres/trust_region_preprocessor.cc b/internal/ceres/trust_region_preprocessor.cc
index f2da3ac..519f851 100644
--- a/internal/ceres/trust_region_preprocessor.cc
+++ b/internal/ceres/trust_region_preprocessor.cc
@@ -32,6 +32,7 @@
 
 #include <numeric>
 #include <string>
+#include <vector>
 
 #include "ceres/callbacks.h"
 #include "ceres/context_impl.h"