二叉搜索树的第k个结点

二叉树算法题中涉及到排序，首先想到中序遍历二叉树

import java.util.*;
/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    int count = 0;
    TreeNode KthNode(TreeNode pRoot, int k)
    {
        if(pRoot == null || count > k)
            return null;
        TreeNode p = pRoot; 
        Stack<TreeNode> LDRStack = new Stack<TreeNode>();
        TreeNode KthNode = null;
        while(p != null || ! LDRStack.isEmpty()){
            while(p != null){
                LDRStack.push(p);
                p = p.left;
            }
            TreeNode node = LDRStack.pop();
            count++;
            if(count == k){
                KthNode = node;
            }
            p = node.right;
        }
        return KthNode;
    }
        

}