klips/cpp/algorithms/graphs/object/graph.cpp

/*##############################################################################
## Author: Shaun Reed                                                         ##
## Legal: All Content (c) 2022 Shaun Reed, all rights reserved                ##
## About: Driver program to test object graph implementation                  ##
##                                                                            ##
## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0   ##
################################################################################
*/

#include "lib-graph.hpp"


int main (const int argc, const char * argv[])
{
  // We could initialize the graph with some localNodes...
  std::vector<Node> localNodes{
      {1, {2, 5}}, // Node 1
      {2, {1, 6}}, // Node 2
      {3, {4, 6, 7}},
      {4, {3, 7, 8}},
      {5, {1}},
      {6, {2, 3, 7}},
      {7, {3, 4, 6, 8}},
      {8, {4, 6}},
  };
  Graph bfsGraphInit(localNodes);


  std::cout << "\n\n##### Breadth First Search #####\n";
  // Or we could use an initializer list...
  // Initialize a example graph for Breadth First Search
  Graph bfsGraph(
      {
          {1, {2, 5}}, // Node 1
          {2, {1, 6}}, // Node 2...
          {3, {4, 6, 7}},
          {4, {3, 7, 8}},
          {5, {1}},
          {6, {2, 3, 7}},
          {7, {3, 4, 6, 8}},
          {8, {4, 6}},
      }
  );
  // The graph traversed in this example is seen in MIT Intro to Algorithms
  // + Chapter 22, Figure 22.3 on BFS
  bfsGraph.BFS(bfsGraph.GetNodeCopy(2));

  std::cout << "\nTesting finding a path between two nodes using BFS...\n";
  // Test finding a path between two nodes using BFS
  auto path = bfsGraph.PathBFS(
      bfsGraph.GetNodeCopy(1), bfsGraph.GetNodeCopy(7)
  );
  // If we were returned an empty path, it doesn't exist
  if (path.empty()) std::cout << "No valid path found!\n";
  else {
    // If we were returned a path, print it
    std::cout << "\nValid path from " << path.front().number
              << " to " << path.back().number << ": ";
    for (const auto &node : path) {
      std::cout << node.number << " ";
    }
    std::cout << std::endl;
  }


  std::cout << "\n\n##### Depth First Search #####\n";
  // Initialize an example graph for Depth First Search
  Graph dfsGraph(
      {
          {1, {2, 4}},
          {2, {5}},
          {3, {5, 6}},
          {4, {2}},
          {5, {4}},
          {6, {6}},
      }
  );
  // The graph traversed in this example is seen in MIT Intro to Algorithms
  // + Chapter 22, Figure 22.4 on DFS
  dfsGraph.DFS();


  std::cout << "\n\n##### Topological Sort #####\n";
  // Initialize an example graph for Depth First Search
  // + The order of initialization is important
  // + To produce the same result as seen in the book
  // ++ If the order is changed, other valid topological orders will be found
  // The book starts on the 'shirt' node (with the number 6, in this example)
  Graph topologicalGraph (
      {
          {1, {4, 5}}, // undershorts
          {2, {5}},    // socks
          {3, {}},     // watch
          {4, {5, 7}}, // pants
          {5, {}},     // shoes
          {6, {8, 7}}, // shirt
          {7, {9}},    // belt
          {8, {9}},    // tie
          {9, {}},     // jacket
      }
  );

  // The graph traversed in this example is seen in MIT Intro to Algorithms
  // + Chapter 22, Figure 22.4 on DFS
  // Unlike the simple-graph example, this final result matches MIT Algorithms
  // + Aside from the placement of the watch node, which is not connected
  // +  This is because the node is visited after all other nodes are finished
  std::vector<Node> order =
      topologicalGraph.TopologicalSort(topologicalGraph.GetNodeCopy(6));
  std::cout << "\nTopological order: ";
  while (!order.empty()) {
    std::cout << order.back().number << " ";
    order.pop_back();
  }
  std::cout << std::endl << std::endl;

  // If we want the topological order to match what is seen in the book
  // + We have to initialize the graph carefully to get this result -
  Graph topologicalGraph2 (
      {
          {6, {8, 7}}, // shirt
          {8, {9}},    // tie
          {7, {9}},    // belt
          {9, {}},     // jacket
          {3, {}},     // watch
          {1, {4, 5}}, // undershorts
          {4, {5, 7}}, // pants
          {5, {}},     // shoes
          {2, {5}},    // socks
      }
  );
  auto order2 = topologicalGraph2.TopologicalSort(*topologicalGraph2.NodeBegin());
  std::cout << "\nTopological order: ";
  while (!order2.empty()) {
    std::cout << order2.back().number << " ";
    order2.pop_back();
  }
  std::cout << std::endl;
}