二叉搜索树的第k个结点

public static TreeNode (TreeNode pRoot, int k) {
    if (pRoot == null || k < 1) {
        return null;
    }
    Stack<TreeNode> stack = new Stack<>();
    int count = 0;
    TreeNode KthNode = null;
    while (pRoot != null || !stack.isEmpty()) {
        while (pRoot != null) {
            stack.push(pRoot);
            pRoot = pRoot.left;
        }
        TreeNode node = stack.pop();
        count++;
        if(count == k){
            KthNode = node;
        }        
        pRoot = node.right;         
    }
    return KthNode;

}