From b5ccbdeda492493c923e71c99e6baf276b318d8e Mon Sep 17 00:00:00 2001
From: Joris van Rantwijk <joris@jorisvr.nl>
Date: Thu, 21 Nov 2024 21:46:39 +0100
Subject: [PATCH] Remove expand_unlabeled_blossom()

---
 cpp/mwmatching.h | 49 +++++++-----------------------------------------
 1 file changed, 7 insertions(+), 42 deletions(-)

diff --git a/cpp/mwmatching.h b/cpp/mwmatching.h
index ccacd0f..3d777f8 100644
--- a/cpp/mwmatching.h
+++ b/cpp/mwmatching.h
@@ -1383,17 +1383,14 @@ public:
         blossom->tree_root = subblossoms.front()->tree_root;
     }
 
-    /** Erase the specified non-trivial blossom. */
-    void erase_nontrivial_blossom(NonTrivialBlossomT* blossom)
-    {
-        nontrivial_blossom.erase(blossom->this_blossom_iterator);
-    }
-
-    /** Expand the specified unlabeled blossom but do not yet delete it. */
-    void expand_unlabeled_blossom_core(NonTrivialBlossomT* blossom)
+    /** Expand and delete the specified T-blossom. */
+    void expand_t_blossom(NonTrivialBlossomT* blossom)
     {
         assert(blossom->parent == nullptr);
-        assert(blossom->label == LABEL_NONE);
+        assert(blossom->label == LABEL_T);
+
+        // Remove label from blossom.
+        remove_blossom_label_t(blossom);
 
         // Remove blossom from the delta2 queue.
         delta2_disable_blossom(blossom);
@@ -1420,26 +1417,6 @@ public:
             // Add unlabeled blossom to the delta2 queue.
             delta2_enable_blossom(sub_blossom);
         }
-    }
-
-    /** Expand and delete the specified unlabeled blossom. */
-    void expand_unlabeled_blossom(NonTrivialBlossomT* blossom)
-    {
-        expand_unlabeled_blossom_core(blossom);
-        erase_nontrivial_blossom(blossom);
-    }
-
-    /** Expand and delete the specified T-blossom. */
-    void expand_t_blossom(NonTrivialBlossomT* blossom)
-    {
-        assert(blossom->parent == nullptr);
-        assert(blossom->label == LABEL_T);
-
-        // Remove label from blossom.
-        remove_blossom_label_t(blossom);
-
-        // Expand the unlabeled blossom.
-        expand_unlabeled_blossom_core(blossom);
 
         // The expanded blossom was part of an alternating tree.
         // We must now reconstruct the part of the alternating tree
@@ -1506,7 +1483,7 @@ public:
         }
 
         // Delete the expanded blossom.
-        erase_nontrivial_blossom(blossom);
+        nontrivial_blossom.erase(blossom->this_blossom_iterator);
     }
 
     /* **********  Augmenting:  ********** */
@@ -1714,8 +1691,6 @@ public:
      * a matched edge to the base of the newly labeled T-blossom.
      * That newly labeled S-blossom is also added to the alternating tree.
      *
-     * Note that this function may expand blossoms that contain vertex "y".
-     *
      * @pre "x" is an S-vertex.
      * @pre "y" is an unlabeled, matched vertex.
      * @pre The top-level blossom that contains "y" has a matched base vertex.
@@ -1727,16 +1702,6 @@ public:
         BlossomT* by = top_level_blossom(y);
         assert(bx->label == LABEL_S);
 
-        // If "y" is part of a zero-dual blossom, expand it.
-        // This would otherwise likely happen through a zero-delta4 step,
-        // so we can just do it now and avoid a substage.
-        NonTrivialBlossomT* ntb = by->nontrivial();
-        while (ntb != nullptr && ntb->dual_var == 0) {
-            expand_unlabeled_blossom(ntb);
-            by = top_level_blossom(y);
-            ntb = by->nontrivial();
-        }
-
         // Assign label T to the top-level blossom that contains vertex "y".
         assign_blossom_label_t(by);
         by->tree_edge = std::make_pair(x, y);