/**

 * Definition for binary tree

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class BSTIterator {

    vector<int> v;

    int pos;

public:

    BSTIterator(TreeNode *root) {

        pos = ;

        stack<TreeNode*> s;

        TreeNode *p = root, *pre = NULL;

        while(p || !s.empty())

        {

            while(p)

            {

                s.push(p);

                p = p->left;

            }

            if(!s.empty())

            {

                p = s.top();

                s.pop();

                v.push_back(p->val);

                p = p->right;

            }

        }

    }

    /** @return whether we have a next smallest number */

    bool hasNext() {

        return pos < v.size();

    }

    /** @return the next smallest number */

    int next() {

        return v[pos++];

    }

};

/**

 * Your BSTIterator will be called like this:

 * BSTIterator i = BSTIterator(root);

 * while (i.hasNext()) cout << i.next();

 */