demo/coloring.cc
author hegyi
Fri, 10 Jun 2005 11:58:03 +0000
changeset 1468 d0ccb2fdeeff
parent 1422 469b3f628dd1
child 1560 01707a8a4ca6
permissions -rw-r--r--
Hopefully, node creation works well, after a small structural consideration.
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#include <vector>
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#include <lemon/smart_graph.h>
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#include <lemon/bin_heap.h>
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#include <lemon/graph_reader.h>
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#include <lemon/graph_to_eps.h>
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using namespace std;
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using namespace lemon;
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int main() {
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  typedef UndirSmartGraph Graph;
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  typedef Graph::Node Node;
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  typedef Graph::NodeIt NodeIt;
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  typedef Graph::UndirEdge UndirEdge;
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  typedef Graph::IncEdgeIt IncEdgeIt;
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  Graph graph;
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  UndirGraphReader<Graph> reader(std::cin, graph);
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  Graph::NodeMap<xy<double> > coords(graph);
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  reader.readNodeMap("coords", coords);
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  reader.run();
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  Graph::NodeMap<int> color(graph, -2);
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  Graph::NodeMap<int> heapMap(graph, -1);
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  BinHeap<Node, int, Graph::NodeMap<int> > heap(heapMap);
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  for (NodeIt it(graph); it != INVALID; ++it) {
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    heap.push(it, countOutEdges(graph, it));
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  }
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  vector<Node> order;
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  while (!heap.empty()) {
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    Node node = heap.top();
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    heap.pop();
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    color[node] = -1;
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    order.push_back(node);
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    for (IncEdgeIt it(graph, node); it != INVALID; ++it) {
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      Node target = graph.runningNode(it); 
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      if (color[target] == -2) {
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	heap.decrease(target, heap[target] - 1);
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      }
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    }
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  }
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  for (int i = order.size() - 1; i >= 0; --i) {
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    set<int> forbidden;
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    for (IncEdgeIt it(graph, order[i]); it != INVALID; ++it) {
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      Node target = graph.runningNode(it); 
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      if (color[target] != -1) {
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	forbidden.insert(color[target]);
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      }
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    }
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    int current = 0;
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    while (forbidden.find(current) != forbidden.end()) ++current;
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    color[order[i]] = current;
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  }
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  ColorSet colorSet;
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  graphToEps(graph, "six_coloring.eps").
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    title("Six Colored Graph").copyright("(C) 2005 LEMON Project").
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    coords(coords).nodeColors(composeMap(colorSet, color)).
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    scaleToA4().run();
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  return 0;
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}