JZ-057-The next node of the binary tree

next node in binary tree

Topic description

Given a binary tree and a node in it, find the next node in inorder traversal order and return. Note that nodes in the tree contain not only left and right child nodes, but also pointers to parent nodes.

topic link : The next node of the binary tree

code

/**
 * 标题：二叉树的下一个结点
 * 题目描述
 * 给定一个二叉树和其中的一个结点，请找出中序遍历顺序的下一个结点并且返回。注意，树中的结点不仅包含左右子结点，同时包含指向父结点的指针。
 * 题目链接
 * https://www.nowcoder.com/practice/9023a0c988684a53960365b889ceaf5e?tpId=13&&tqId=11210&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking
 */
public class Jz57 {

    /**
     * 方法：如果一个节点的右子树不为空，那么该节点的下一个节点是右子树的最左节点；
     * 否则，向上找第一个左链接指向的树包含该节点的祖先节点。
     *
     * @param pNode
     * @return
     */
    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 parent = pNode.next;
                if (parent.left == pNode) {
                    return parent;
                }
                pNode = pNode.next;
            }
        }
        return null;
    }

    public static void main(String[] args) {

    }
}

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