剑指offer-二叉搜索树的第k个结点

/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

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

    }

}
*/
public class Solution {
    private TreeNode node =null;
    private int pos = 0;
    TreeNode KthNode(TreeNode pRoot, int k)
    {
        if(null == pRoot){
            return null;
        }
        //左子树
        KthNode(pRoot.left,k);
        //当前节点
        pos++;
        if(pos == k && node == null){
            node = pRoot;
            return node;
        }
        //右子树
        KthNode(pRoot.right,k);
        return node;
    }
    

}