fix: endless loop in initial ggg bipartitioner (#37)

The initial greedy graph growing bipartitioner could get stuck in an
endless loop if the perfectly balanced block weight of one block is set
to 0. To fix this, change < to <=.

kaminpar-shm/initial_partitioning/initial_ggg_bipartitioner.cc

@@ -51,6 +51,7 @@ void InitialGGGBipartitioner::fill_bipartition() {
     if (_marker.get(start_node)) {
       start_node = _marker.first_unmarked_element();
     }
+    KASSERT(start_node < _graph->n(), "no unmarked node found");
 
     _queue.push(start_node, compute_gain(start_node));
     _marker.set<true>(start_node);
@@ -86,7 +87,7 @@ void InitialGGGBipartitioner::fill_bipartition() {
         }
       });
     }
-  } while (_block_weights[V2] < _p_ctx->block_weights.perfectly_balanced(V2));
+  } while (_block_weights[V2] <= _p_ctx->block_weights.perfectly_balanced(V2));
 }
 
 [[nodiscard]] EdgeWeight InitialGGGBipartitioner::compute_gain(const NodeID u) const {