coding_codes/fluery.cpp at master · ranarag/coding_codes · GitHub

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#include <iostream>
#include <string.h>
#include <algorithm>
#include <list>
using namespace std;

class Graph
{
  int V;
  list<int> *adj;
public:

  Graph(int V)  { this->V = V;  adj = new list<int>[V];  }
  ~Graph()      { delete [] adj;  }


  void addEdge(int u, int v) {  adj[u].push_back(v); adj[v].push_back(u); }
  void rmvEdge(int u, int v);


  void printEulerTour();
  void printEulerUtil(int s);


  int DFSCount(int v, bool visited[]);


  bool isValidNextEdge(int u, int v);
};


void Graph::printEulerTour()
{

  int u = 0;
  for (int i = 0; i < V; i++)
      if (adj[i].size() & 1)
        {   u = i; break;  }


  printEulerUtil(u);
  cout << endl;
}


void Graph::printEulerUtil(int u)
{

  list<int>::iterator i;
  for (i = adj[u].begin(); i != adj[u].end(); ++i)
  {
      int v = *i;


      if (v != -1 && isValidNextEdge(u, v))
      {
          cout << u+1 << "->" << v+1 << "  ";
          rmvEdge(u, v);
          printEulerUtil(v);
      }
  }
}


bool Graph::isValidNextEdge(int u, int v)
{

  int count = 0;
  list<int>::iterator i;
  for (i = adj[u].begin(); i != adj[u].end(); ++i)
     if (*i != -1)
        count++;
  if (count == 1)
    return true;


  bool visited[V];
  memset(visited, false, V);
  int count1 = DFSCount(u, visited);


  rmvEdge(u, v);
  memset(visited, false, V);
  int count2 = DFSCount(u, visited);


  addEdge(u, v);


  return (count1 > count2)? false: true;
}


void Graph::rmvEdge(int u, int v)
{

  list<int>::iterator iv = find(adj[u].begin(), adj[u].end(), v);
  *iv = -1;


  list<int>::iterator iu = find(adj[v].begin(), adj[v].end(), u);
  *iu = -1;
}


int Graph::DFSCount(int v, bool visited[])
{

  visited[v] = true;
  int count = 1;


  list<int>::iterator i;
  for (i = adj[v].begin(); i != adj[v].end(); ++i)
      if (*i != -1 && !visited[*i])
          count += DFSCount(*i, visited);

  return count;
}


  int main(void){
cout<<"enter no. of nodes\n";
int n;
cin>>n;
  Graph g1(n);
 cout<<"enter no.of edges\n";
int m;
int i,x,y;
cin>>m;
cout<<"enter edges one by one\n";
for(i=0;i<m;i++){
        cin>>x>>y;
       g1.addEdge(x-1,y-1);
}

  g1.printEulerTour();


}