【剑指Offer】8. 二叉树的下一个结点

public class TreeLinkNode {

    int val;
    TreeLinkNode left = null;
    TreeLinkNode right = null;
    TreeLinkNode next = null;

    TreeLinkNode(int val) {
        this.val = val;
    }
}

/*
public class TreeLinkNode {
    int val;
    TreeLinkNode left = null;
    TreeLinkNode right = null;
    TreeLinkNode next = null;

    TreeLinkNode(int val) {
        this.val = val;
    }
}
*/
public class Solution {
    public TreeLinkNode GetNext(TreeLinkNode pNode) {
        if(pNode.right != null) {
            TreeLinkNode node = pNode.right;
            while(node.left != null) 
                node = node.left;
            return node;
        }else {
            while(pNode.next != null) {
                TreeLinkNode parens = pNode.next;
                if(parens.left == pNode)
                    return parens;
                pNode = pNode.next;
            }
        }
        return null;
    }
}

static  ArrayList<TreeLinkNode> a=new ArrayList<>();
      public static void InOrder(TreeLinkNode pRoot){
            if (pRoot != null) {
                InOrder(pRoot.left);
                a.add(pRoot);
                InOrder(pRoot.right);
            }
        }


        public  TreeLinkNode GetNext(TreeLinkNode pNode)
        {
            TreeLinkNode p=pNode;
            int i;
            while (pNode.next!=null)
              {
                  pNode=pNode.next;

              }
              InOrder(pNode);
              for( i=0;i<a.size();i++)
              {
                  if(p==a.get(i))
                  {
                      return i == a.size()-1?null:a.get(i+1);
                  }
              }
              return null;

         }