grid_example.cc

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
  copies or substantial portions of the Software.
 
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
*/
 
#include <iostream>
#include <numbers>
#include <grid.H>
#include <tpl_graph.H>
 
using namespace std;
using namespace Aleph;
 
// A simple structure to hold node coordinates
struct Coordinate {
  size_t row, col;
  Coordinate() : row(0), col(0) {}
  Coordinate(size_t r, size_t c) : row(r), col(c) {}
};
 
// Functor to initialize node coordinates
struct InitNode {
  template <class Graph>
  void operator()(Graph& /*g*/, typename Graph::Node* n, size_t r, size_t c) {
    n->get_info() = Coordinate(r, c);
  }
};
 
// Functor to initialize arc weights
// For a grid, we might set orthogonal moves to cost 1.0 and diagonal to 1.414 (sqrt(2))
struct InitArc {
  template <class Graph>
  void operator()(Graph& g, typename Graph::Arc* a, size_t /*r*/, size_t /*c*/) {
    // Determine if the connection is diagonal or orthogonal based on coordinates
    auto src_info = g.get_src_node(a)->get_info();
    auto tgt_info = g.get_tgt_node(a)->get_info();
    
    bool is_diagonal = (src_info.row != tgt_info.row) and (src_info.col != tgt_info.col);
    a->get_info() = is_diagonal ? std::numbers::sqrt2 : 1.0;
  }
};
 
int main() {
  cout << "========================================" << endl;
  cout << "        Grid Graph Generation Example" << endl;
  cout << "========================================" << endl;
 
  // We define a graph with Coordinate as node info and double as arc info
  List_Graph<Graph_Node<Coordinate>, Graph_Arc<double>> g;
  
  // We use our custom functors to initialize the nodes and arcs during generation
  Build_Grid<decltype(g), InitNode, InitArc> builder;
  
  const size_t rows = 4;
  const size_t cols = 4;
  
  cout << "\nBuilding a " << rows << " x " << cols << " grid..." << endl;
  // Note: parameters are (graph, width, height)
  builder(g, cols, rows);
  
  cout << "Grid successfully built!" << endl;
  cout << "Number of nodes: " << g.get_num_nodes() << endl;
  cout << "Number of arcs: " << g.get_num_arcs() << endl;
  
  cout << "\nSample of connections from the bottom-right node (" << rows-1 << ", " << cols-1 << "):" << endl;
  
  // Find the node at (rows-1, cols-1)
  List_Graph<Graph_Node<Coordinate>, Graph_Arc<double>>::Node* last_node = nullptr;
  for (auto it = g.get_node_it(); it.has_curr(); it.next()) {
    auto n = it.get_curr();
    if (n->get_info().row == rows - 1 and n->get_info().col == cols - 1) {
      last_node = n;
      break;
    }
  }
  
  if (last_node) {
    // In Aleph-w, arcs are directed from the node that created them. 
    // Build_Grid connects node (i,j) to its previously created neighbors (left, up, diags).
    // So the last node has outgoing arcs to its top, left, and upper-left neighbors.
    for (auto it = g.get_out_it(last_node); it.has_curr(); it.next()) {
      auto a = it.get_curr();
      auto tgt = g.get_tgt_node(a);
      cout << "  -> Connected to node (" << tgt->get_info().row << ", " << tgt->get_info().col 
           << ") with weight " << a->get_info() << endl;
    }
  }
 
  cout << "\n========================================" << endl;
  return 0;
}