Size of a binary tree with non recursive method Java

Question

Hello I\'m trying to write a non recursive method for getting the size of a node since recursion in Java is expensive. This would include the number of child nodes + 1 (itse

Answer 1

Here is a C implementation. RealSkeptic's method above was not that intuitive to me. I provide comments and it should be pretty easy to follow.

int sizeOfBsTree_nonRec(TreeNode *root)
{
    if (root == NULL) {
        return 0;
    }

    int size = 0;
    Stack S;
    initializeStack(&S);

    // Push to the stack all Nodes in the (sub)tree and
    // increase the counter when you pop one out
    push(root, &S);
    while(!isStackEmpty(&S)){
        root = pop(&S);
        size++;

        if (root->right != NULL)
            push(root->right, &S);
        if (root->left != NULL)
            push(root->left, &S);
    }

    return size;
}