Sunday 12 April 2020

Algorithm for Inorder Tree Traversals : Iterative Model(Non-Recursive way)



import java.util.Stack;

//Inorder Tree Traversals : Iterative Model(Non-Recursive way)

class BinaryTreeInOrderTraversalIterativeModel {
     class TreeNode {
            TreeNode left, right;
            int data; // considering integer data.
      
            public TreeNode(int dataItem) {
                  this.data = dataItem;
                  left = null;
                  right = null;
            }
     }
      
      TreeNode root;
       BinaryTreeInOrderTraversalIterativeModel() {
             root = null;
       }
      
       void printInOrderTraversal(TreeNode treeNode) {
             if(treeNode == null)
                    return;
             Stack<TreeNode> s = new Stack<TreeNode>();
             TreeNode currentNode = root;
            
             while(!s.isEmpty() || currentNode != null) {
                    if(currentNode != null) {
                          s.push(currentNode);
                          currentNode = currentNode.left;
                    } else {
                          currentNode = s.pop();
                           System.out.println(currentNode.data);
                          currentNode = currentNode.right;
                    }
             }


       }
      
       void printInOrder() {
             printInOrderTraversal(root);
       }

       public static void main(String[] args) {
             BinaryTreeInOrderTraversalIterativeModel tree = new BinaryTreeInOrderTraversalIterativeModel();
             tree.root = new TreeNode(1);
       
             tree.root.left = new TreeNode(2);
             tree.root.right = new TreeNode(3);
       
             tree.root.left.left = new TreeNode(4);
             tree.root.left.right = new TreeNode(5);
       
             tree.root.right.left = new TreeNode(6);
             tree.root.right.right = new TreeNode(7);
       
             tree.printInOrder();
       }

}

//Time Complexity: O(n). Space Complexity: O(n).


Thanks..!!

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