Fix newly appeared clang-tidy readability-function-cognitive-complexity errors (#366)

Author: aobolensk

Diff for: tasks/mpi/example/include/ops_mpi.hpp

@@ -18,6 +18,10 @@ class TestTaskMPI : public ppc::core::Task {
  private:
   std::vector<int> input_, output_;
   int rc_size_{};
+
+  void MultiplyMatrixBasedOnRank();
+  void MultiplyRowMajor();
+  void MultiplyColumnMajor();
 };
 
 }  // namespace nesterov_a_test_task_mpi

Diff for: tasks/mpi/example/src/ops_mpi.cpp

@@ -25,26 +25,40 @@ bool nesterov_a_test_task_mpi::TestTaskMPI::ValidationImpl() {
 }
 
 bool nesterov_a_test_task_mpi::TestTaskMPI::RunImpl() {
+  MultiplyMatrixBasedOnRank();
+  return true;
+}
+
+void nesterov_a_test_task_mpi::TestTaskMPI::MultiplyMatrixBasedOnRank() {
   int rank = -1;
   MPI_Comm_rank(MPI_COMM_WORLD, &rank);
 
-  auto multiply = [this](bool row_major) {
-    for (int i = 0; i < rc_size_; ++i) {
-      for (int j = 0; j < rc_size_; ++j) {
-        int sum = 0;
-        for (int k = 0; k < rc_size_; ++k) {
-          int a = input_[(row_major ? i : k) * rc_size_ + (row_major ? k : i)];
-          int b = input_[(row_major ? k : j) * rc_size_ + (row_major ? j : k)];
-          sum += a * b;
-        }
-        output_[(i * rc_size_) + j] += sum;
+  if (rank == 0) {
+    MultiplyRowMajor();
+  } else {
+    MultiplyColumnMajor();
+  }
+  MPI_Barrier(MPI_COMM_WORLD);
+}
+
+void nesterov_a_test_task_mpi::TestTaskMPI::MultiplyRowMajor() {
+  for (int i = 0; i < rc_size_; ++i) {
+    for (int j = 0; j < rc_size_; ++j) {
+      for (int k = 0; k < rc_size_; ++k) {
+        output_[(i * rc_size_) + j] += input_[(i * rc_size_) + k] * input_[(k * rc_size_) + j];
       }
     }
-  };
+  }
+}
 
-  multiply(rank == 0);
-  MPI_Barrier(MPI_COMM_WORLD);
-  return true;
+void nesterov_a_test_task_mpi::TestTaskMPI::MultiplyColumnMajor() {
+  for (int j = 0; j < rc_size_; ++j) {
+    for (int k = 0; k < rc_size_; ++k) {
+      for (int i = 0; i < rc_size_; ++i) {
+        output_[(i * rc_size_) + j] += input_[(i * rc_size_) + k] * input_[(k * rc_size_) + j];
+      }
+    }
+  }
 }
 
 bool nesterov_a_test_task_mpi::TestTaskMPI::PostProcessingImpl() {