#include <iostream>
#include <stdlib.h>

#include "Array.h"
#include "Hash.h"
#include "Graph.h"
#include "UnionFind.h"
#include "Maze.h"

#include "test_utilities.h"

#define DEBUG(x) 
//#define DEBUG(x) x

int
main() {
  Maze m;

  std::cin >> m;

  const Graph & g = m.graph();
  Array<int> vertex_ids = g.vertices();

  int start_vertex = m.get_start_vertex();
  int end_vertex = m.get_end_vertex();

  HashTable<int,UnionFind *> components(NULL);

  components[start_vertex] = new UnionFind;
  components[end_vertex] = new UnionFind;

  if (g.edge_exists(start_vertex,end_vertex))
    components[start_vertex]->merge(*components[end_vertex]);

  DEBUG(std::cerr << "vertices:\n" << vertex_ids << std::endl;);

  // randomly permute the vertices
  for (int i = 1;  i < vertex_ids.size();  ++i) {
    int j = random() % (i+1);
    if (i != j) {
      int tmp = vertex_ids[i];
      vertex_ids[i] = vertex_ids[j];
      vertex_ids[j] = tmp;
    }
  }

  DEBUG(std::cerr << "permuted vertices:\n" << vertex_ids << std::endl;)

  for (int i = 0;  i < vertex_ids.size();  ++i) {
    int v = vertex_ids[i];

    if (i % 100 == 99) std::cerr << ".";

    DEBUG(std::cerr << "considering vertex " << v << std::endl;);

    if (components[v]) continue;
    
    DEBUG(std::cerr << "(doesn't yet exist)" << std::endl;);

    Array<int> built_nbrs; 
    Array<UnionFind *> nbr_comps;
    {
      HashTable<UnionFind *, bool> nbr_comps_hash;

      Array<int> nbrs = g.nbrs(v);
      for (int j = 0;  j < nbrs.size();  ++j) {
	int w = nbrs[j];
	if (components[w]) {
	  built_nbrs[built_nbrs.size()] = w;
	  nbr_comps_hash[components[w]->find()];
	}
	nbr_comps = nbr_comps_hash.keys();
      }
    }

    DEBUG(std::cerr << built_nbrs.size() << " neighbors with " << nbr_comps.size() << " components" << std::endl;);

    // if # nbrs <= 1 add cell
    // or if # nbr_comps > 1 add cell

    if (built_nbrs.size() <= 1 || nbr_comps.size() > 1) {

    // or, if #nbrs == #comps add cell
    //if (built_nbrs.size() == nbr_comps.size()) {
      
      DEBUG(std::cerr << "adding cell" << std::endl;);

      components[v] = new UnionFind;
      for (int j = 0;  j < nbr_comps.size();  ++j) {
	DEBUG(std::cerr << "merging v's component with " << j << "th neighboring component"<< std::endl;);
	components[v]->merge(*nbr_comps[j]);
      }

      DEBUG(std::cerr << "number of components is now " << UnionFind::n_components() << std::endl;);
    }
  }

  std::cerr << std:: endl;

  for (int i = 0;  i < vertex_ids.size();  ++i) {
    int v = vertex_ids[i];
    if (! components[v]) {

      DEBUG(std::cerr << "erasing vertex " << v << std::endl;);

      Array<int> loc = m.loc_of_vertex(v);
      m.set_text_at(loc[0], loc[1], ' ');
    }
  }

  std::cout << m;
}