二叉搜索树与双向链表——java

输入一棵二叉搜索树，将该二叉搜索树转换成一个排序的双向链表。要求不能创建任何新的结点，只能调整树中结点指针的指向

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

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

    }

}
*/
public class Solution {
    public TreeNode Convert(TreeNode pRootOfTree) {
        if(pRootOfTree==null)
            return null;
        if(pRootOfTree.left==null&&pRootOfTree.right==null)
            return pRootOfTree;
        TreeNode left = Convert(pRootOfTree.left);
        TreeNode p = left;
        while(p!=null&&p.right!=null)
            p=p.right;
        if(left!=null){
            p.right=pRootOfTree;
            pRootOfTree.left=p;
        }
        TreeNode right = Convert(pRootOfTree.right);
        if(right!=null){
            pRootOfTree.right=right;
            right.left=pRootOfTree;
        }
        return left!=null?left:pRootOfTree;
    }
}