Changeset 647:dcba640438c7 in lemon-main

Timestamp:

05/06/09 14:37:44 (16 years ago)

Author:

Peter Kovacs <kpeter@…>

Branch:

default

Phase:

public

Message:

Bug fixes in connectivity.h (#285)

• Bug fix in tree().
• Rename simpleDigraph() to simpleGraph() (it works for both directed and undirected graphs).
• Possibly faster implementation for parallelFree() and simpleGraph().

File:

• lemon/connectivity.h (modified) (3 diffs)

lemon/connectivity.h

@@ -1371 +1371 @@
     typedef typename Graph::NodeIt NodeIt;
     typedef typename Graph::Arc Arc;
+    if (NodeIt(graph) == INVALID) return true;
     Dfs<Graph> dfs(graph);
     dfs.init();
@@ -1546 +1547 @@
   ///
   /// Returns true when there are not parallel edges in the graph.
-  template <typename Digraph>
-  bool parallelFree(const Digraph& digraph) {
-    typename Digraph::template NodeMap<bool> reached(digraph, false);
-    for (typename Digraph::NodeIt n(digraph); n != INVALID; ++n) {
-      for (typename Digraph::OutArcIt a(digraph, n); a != INVALID; ++a) {
-        if (reached[digraph.target(a)]) return false;
-        reached.set(digraph.target(a), true);
-      }
-      for (typename Digraph::OutArcIt a(digraph, n); a != INVALID; ++a) {
-        reached.set(digraph.target(a), false);
-      }
+  template <typename Graph>
+  bool parallelFree(const Graph& graph) {
+    typename Graph::template NodeMap<int> reached(graph, 0);
+    int cnt = 1;
+    for (typename Graph::NodeIt n(graph); n != INVALID; ++n) {
+      for (typename Graph::OutArcIt a(graph, n); a != INVALID; ++a) {
+        if (reached[graph.target(a)] == cnt) return false;
+        reached[graph.target(a)] = cnt;
+      }
+      ++cnt;
     }
     return true;
@@ -1566 +1566 @@
   /// Returns true when there are not loop edges and parallel edges in
   /// the graph.
-  template <typename Digraph>
-  bool simpleDigraph(const Digraph& digraph) {
-    typename Digraph::template NodeMap<bool> reached(digraph, false);
-    for (typename Digraph::NodeIt n(digraph); n != INVALID; ++n) {
-      reached.set(n, true);
-      for (typename Digraph::OutArcIt a(digraph, n); a != INVALID; ++a) {
-        if (reached[digraph.target(a)]) return false;
-        reached.set(digraph.target(a), true);
-      }
-      for (typename Digraph::OutArcIt a(digraph, n); a != INVALID; ++a) {
-        reached.set(digraph.target(a), false);
-      }
-      reached.set(n, false);
+  template <typename Graph>
+  bool simpleGraph(const Graph& graph) {
+    typename Graph::template NodeMap<int> reached(graph, 0);
+    int cnt = 1;
+    for (typename Graph::NodeIt n(graph); n != INVALID; ++n) {
+      reached[n] = cnt;
+      for (typename Graph::OutArcIt a(graph, n); a != INVALID; ++a) {
+        if (reached[graph.target(a)] == cnt) return false;
+        reached[graph.target(a)] = cnt;
+      }
+      ++cnt;
     }
     return true;