题解 | #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 Solution {
    public TreeLinkNode GetNext(TreeLinkNode pNode) {
        if(pNode.right != null) {
            return getNode(pNode.right);
        }
        if(pNode.next != null) {
            if(pNode.next.left == pNode) {
                return pNode.next;
            }
            return getRootNode(pNode.next, pNode);
        }
        return null;

    }
    

    private TreeLinkNode getNode(TreeLinkNode pNode) {
        if(pNode.left != null) {
            return getNode(pNode.left);
        }
        return pNode;
    }
    
    private TreeLinkNode getRootNode(TreeLinkNode next,TreeLinkNode pNode) {
        if(next.next != null) {
            return getRootNode(next.next, next);
        }
        if(next.right == pNode) {
            return null;
        }
        return next;
    }
    
}