Working version of Kruskal's algorithm. The running time is very bad though.

src/graph.c

@@ -17,7 +17,7 @@
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
-    $Id: graph.c,v 1.1.2.2 2001/10/28 22:42:49 guus Exp $
+    $Id: graph.c,v 1.1.2.3 2001/10/29 13:14:57 guus Exp $
 */
 
 /* We need to generate two trees from the graph:
@@ -40,6 +40,7 @@
 
 #include <syslog.h>
 #include "config.h"
+#include <string.h>
 
 #include <avl_tree.h>
 
@@ -50,7 +51,7 @@
 #include "system.h"
 
 /* Implementation of Kruskal's algorithm.
-   Running time: O(E)
+   Running time: O(EN)
    Please note that sorting on weight is already done by add_edge().
 */
 
@@ -62,6 +63,7 @@ void mst_kruskal(void)
   connection_t *c;
   int nodes = 0;
   int safe_edges = 0;
+  int skipped;
 
   syslog(LOG_DEBUG, _("Running Kruskal's algorithm:"));
 
@@ -74,6 +76,10 @@ void mst_kruskal(void)
       nodes++;
     }
 
+  /* Starting point */
+  
+  ((edge_t *)edge_weight_tree->head->data)->from->status.visited = 1;
+
   /* Clear MST status on connections */
 
   for(node = connection_tree->head; node; node = node->next)
@@ -84,7 +90,8 @@ void mst_kruskal(void)
 
   /* Add safe edges */
 
-  for(node = edge_weight_tree->head; node; node = node->next)
+  while(safe_edges < nodes - 1)
+  for(skipped = 0, node = edge_weight_tree->head; node; node = node->next)
     {
 // Algorithm should work without this:
 //      if(safe_edges = nodes - 1)
@@ -92,8 +99,11 @@ void mst_kruskal(void)
 
       e = (edge_t *)node->data;
 
-      if(e->from->status.visited && e->to->status.visited)
+      if(e->from->status.visited == e->to->status.visited)
+        {
+          skipped = 1;
           continue;
+        }
 
       e->from->status.visited = 1;
       e->to->status.visited = 1;
@@ -103,6 +113,9 @@ void mst_kruskal(void)
       safe_edges++;
 
       syslog(LOG_DEBUG, _("Adding safe edge %s - %s weight %d"), e->from->name, e->to->name, e->weight);
+
+      if(skipped)
+        break;
     }
 
   syslog(LOG_DEBUG, _("Done."));
@@ -172,8 +185,11 @@ void sssp_bfs(void)
                   check->status.visited = 1;
                   check->nexthop = (n->nexthop == myself) ? n : n->nexthop;
                   check->via = check; /* FIXME: only if !(e->options & INDIRECT), otherwise use n->via */
-                  avl_insert_before(todo_tree, todo_tree->head, to);
+                  node = avl_alloc_node();
+                  node->data = check;
+                  avl_insert_before(todo_tree, from, node);
                   visited++;
+                  syslog(LOG_DEBUG, _("Node %s nexthop %s via %s"), check->name, check->nexthop->name, check->via->name);
                 }
             }
 
@@ -183,6 +199,8 @@ void sssp_bfs(void)
 
   syslog(LOG_DEBUG, _("Done."));
 
+  avl_free_tree(todo_tree);
+
   if(visited != nodes)
     {
       syslog(LOG_ERR, _("Implementation of BFS algorithm is screwed: %d nodes, visited %d"), nodes, visited);

src/graph.h

@@ -0,0 +1,25 @@
+/*
+    graph.h -- header for graph.c
+    Copyright (C) 2001 Guus Sliepen <guus@sliepen.warande.net>,
+                  2001 Ivo Timmermans <itimmermans@bigfoot.com>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+    $Id: graph.h,v 1.1.2.1 2001/10/29 13:14:57 guus Exp $
+*/
+
+extern void mst_kruskal(void);
+extern void mst_prim(void);
+extern void sssp_bfs(void);