Iterative Pre, Post And Inorder Traversals Of Binary Tree

void iterativePrePostInTraversal(Node *root)

{

    // pair of node and number of visits to the i-th node.

    //  if number of visits=0, then print in pre and move to left.

    //  if number of visits=1, then print in In and move to right.

    //  if number of visits=2, then print in post and pop the value at top;

    stack<pair<Node *, int>> st;

    vector<int> pre, post, in;

    st.push({root, 0});

    pair<Node *, int> temp;

    while (!st.empty())

    {

        temp = st.top();

        if (temp.second == 0)

        {

            st.top().second++;

            pre.push_back(temp.first->data);

            if (temp.first->left)

                st.push({temp.first->left, 0});

        }

        else if (temp.second == 1)

        {

            st.top().second++;

            in.push_back(temp.first->data);

            if (temp.first->right)

                st.push({temp.first->right, 0});

        }

        else

        {

            st.pop();

            post.push_back(temp.first->data);

        }

    }

   

    for (auto it : pre)

        cout << it << " ";

    cout << endl;

    for (auto it : in)

        cout << it << " ";

    cout << endl;

    for (auto it : post)

        cout << it << " ";

}