From fb4e0aebd6d118090312eb6f9513aa0ba73510c3 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <doug.gregor@gmail.com>
Date: Fri, 18 Mar 2005 04:47:40 +0000
Subject: [PATCH] Remove-last-vertex optimization (Vikram Shrowty)

[SVN r27731]
---
 include/boost/graph/detail/adjacency_list.hpp | 36 ++++++++++---------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/include/boost/graph/detail/adjacency_list.hpp b/include/boost/graph/detail/adjacency_list.hpp
index 7383e813..bbaa29e6 100644
--- a/include/boost/graph/detail/adjacency_list.hpp
+++ b/include/boost/graph/detail/adjacency_list.hpp
@@ -1882,8 +1882,10 @@ namespace boost {
         typedef typename Graph::edge_parallel_category edge_parallel_category;
         g.m_vertices.erase(g.m_vertices.begin() + u);
         vertex_descriptor V = num_vertices(g);
-        for (vertex_descriptor v = 0; v < V; ++v)
-          reindex_edge_list(g.out_edge_list(v), u, edge_parallel_category());
+        if (u != V) {
+          for (vertex_descriptor v = 0; v < V; ++v)
+            reindex_edge_list(g.out_edge_list(v), u, edge_parallel_category());
+        }
       }
 
       template <class Graph, class vertex_descriptor>
@@ -1916,21 +1918,23 @@ namespace boost {
         g.m_vertices.erase(g.m_vertices.begin() + u);
         vertex_descriptor V = num_vertices(g);
         vertex_descriptor v;
-        for (v = 0; v < V; ++v)
-          reindex_edge_list(g.out_edge_list(v), u, 
-                            edge_parallel_category());
-        for (v = 0; v < V; ++v)
-          reindex_edge_list(in_edge_list(g, v), u, 
-                            edge_parallel_category());
+        if (u != V) {
+          for (v = 0; v < V; ++v)
+            reindex_edge_list(g.out_edge_list(v), u, 
+                              edge_parallel_category());
+          for (v = 0; v < V; ++v)
+            reindex_edge_list(in_edge_list(g, v), u, 
+                              edge_parallel_category());
 
-        typedef typename Graph::EdgeContainer Container;
-        typedef typename Container::iterator Iter;
-        Iter ei = g.m_edges.begin(), ei_end = g.m_edges.end();
-        for (; ei != ei_end; ++ei) {
-          if (ei->m_source > u)
-            --ei->m_source;
-          if (ei->m_target > u)
-            --ei->m_target;
+          typedef typename Graph::EdgeContainer Container;
+          typedef typename Container::iterator Iter;
+          Iter ei = g.m_edges.begin(), ei_end = g.m_edges.end();
+          for (; ei != ei_end; ++ei) {
+            if (ei->m_source > u)
+              --ei->m_source;
+            if (ei->m_target > u)
+              --ei->m_target;
+          }
         }
       }