99. Recover Binary Search Tree

class Solution {
    public void recoverTree(TreeNode root) {
        TreeNode cur=root,pre=null,node1=null,node2=null, p=null;
        while(cur!=null)
        {
            if(cur.left!=null)
            {
                pre=cur.left;
                while(pre.right!=null&&pre.right!=cur)
                    pre=pre.right;
                
                if(pre.right==null)
                {
                    pre.right=cur;
                    cur=cur.left;
                }
                else
                {
                    if(p!=null&&cur!=null&&p.val>cur.val)
                    {
                        if(node1==null)
                            node1=p;
                        node2=cur;
                    }
                    pre.right=null;
                    p=cur;
                    cur=cur.right;
                }
            }
            else
            {
                if(p!=null&&cur!=null&&p.val>cur.val)
                {
                    if(node1==null)
                        node1=p;
                    node2=cur;
                }
                p=cur;
                cur=cur.right;
            }
        }
        int tmp=node1.val;
        node1.val=node2.val;
        node2.val=tmp;
    }
}