dfs graph iterative code example

Example 1: iterative dfs in tree

import java.util.Stack; 

class Node 
{ 
    int data; 
    Node left, right; 
  
    public Node(int item) 
    { 
        data = item; 
        left = right = null; 
    } 
} 

@SuppressWarnings("unchecked")
class BinaryTree
{
    Node root;
    public static void inOrderTraversal(Node root)
    {
      Stack<Node> stack = new Stack();
      Node curr = root;
      while (!stack.empty() || curr != null)
      {
        if (curr != null)
        {
          stack.push(curr);
          curr = curr.left;
        }
        else
        {
          curr = stack.pop();
          System.out.print(curr.data + " ");
          curr = curr.right;
        }
      }
    }

}

Example 2: depth first search stack

DFS-iterative (G, s):                                   //Where G is graph and s is source vertex
      let S be stack
      S.push( s )            //Inserting s in stack 
      mark s as visited.
      while ( S is not empty):
          //Pop a vertex from stack to visit next
          v  =  S.top( )
         S.pop( )
         //Push all the neighbours of v in stack that are not visited   
        for all neighbours w of v in Graph G:
            if w is not visited :
                     S.push( w )         
                    mark w as visited


    DFS-recursive(G, s):
        mark s as visited
        for all neighbours w of s in Graph G:
            if w is not visited:
                DFS-recursive(G, w)