सी ++ प्रोग्राम ग्राफ में दो नोड्स के बीच पथ खोजने के लिए

इस कार्यक्रम में हम दिए गए ग्राफ पर डीएफएस का उपयोग करके पता लगा सकते हैं कि क्या दो नोड्स के बीच पथ मौजूद है।

एल्गोरिदम

Begin
   function isReach() is a recursive function to check whether d is reachable to s :
   A) Mark all the vertices as unvisited.
   B) Mark the current node as visited and enqueue it and it will be used to get all adjacent vertices of a vertex
   C) Dequeue a vertex from queue and print it
   D) Get all adjacent vertices of the dequeued vertex s
   E) If an adjacent has not been visited, then mark it visited and enqueue it
   F) If this adjacent node is the destination node, then return true else continue to BFS
End

उदाहरण

#include <iostream>
#include <list>
using namespace std;
class G {
   int n;
   list<int> *adj;
   public:
      //declaration of functions
      G(int n);
      void addEd(int v, int u);
      bool isReach(int s, int d);
};
G::G(int n) {
   this->n = n;
   adj = new list<int> [n];
}
void G::addEd(int v, int u) //add edges to the graph {
   adj[v].push_back(u);
}
bool G::isReach(int s, int d) {
   if (s == d)
      return true;
      //Mark all the vertices as unvisited.
      bool *visited = new bool[n];
   for (int i = 0; i < n; i++)
      visited[i] = false;
      list<int> queue;
      //Mark the current node as visited and enqueue it and it will be used to get all adjacent vertices of a vertex
      visited[s] = true;
      queue.push_back(s);
      list<int>::iterator i;
   while (!queue.empty()) {
      s = queue.front();
      queue.pop_front(); //Dequeue a vertex from queue and print it
      //If an adjacent has not been visited, then mark it visited and enqueue it
      for (i = adj[s].begin(); i != adj[s].end(); ++i) {
         if (*i == d)
            return true;
            // If this adjacent node is the destination node, then return true else continue to BFS
         if (!visited[*i]) {
            visited[*i] = true;
            queue.push_back(*i);
         }
      }
   }
   return false;
}
int main() {
   G g(4);
   g.addEd(1, 3);
   g.addEd(0, 1);
   g.addEd(2, 3);
   g.addEd(1, 0);
   g.addEd(2, 1);
   g.addEd(3, 1);
   cout << "Enter the source and destination vertices: (0-3)";
   int a, b;
   cin >> a >> b;
   if (g.isReach(a, b))
      cout << "\nThere is a path from " << a << " to " << b;
   else
      cout << "\nThere is no path from " << a << " to " << b;
      int t;
      t = a;
      a = b;
      b = t;
   if (g.isReach(a, b))
      cout << "\nThere is a path from " << a << " to " << b;
   else
      cout << "\nThere is no path from " << a << " to " << b;
   return 0;
}

आउटपुट

Enter the source and destination vertices: (0-3)
There is a path from 3 to 1
There is a path from 1 to 3