[DOC] Clear some comments.

src/layout/hierarchical_binning.cpp

@@ -329,14 +329,12 @@ size_t hierarchical_binning::backtracking(std::vector<std::vector<std::pair<size
     assert(trace_i == 0 || trace_j == 0);
     if (trace_i == 0u && trace_j > 0u) // the last UBs get merged into the remaining TB
     {
+        // we are in the first row, merging the remaining UBs into the last TB (TB-0)
         backtrack_merged_bin(trace_j, 0, bin_id, high_level_max_id, high_level_max_size, true);
-
-        // std::cout << "\t I am now at " << trace_i << "," << trace_j << std::endl;
     }
     else if (trace_j == 0u) // the last UB is split into the remaining TBs
     {
-        // we only arrive here if the first user bin (UB-0) wasn't merged with some before so it is safe to assume
-        // that the bin was split (even if only into 1 bin).
+        // we are in the first column, splitting the last UB (UB-0) into the remaining TBs (even if only into 1 bin).
         backtrack_split_bin(trace_j, trace_i + 1, bin_id, high_level_max_id, high_level_max_size);
     }