Flatten Binary Tree to Linked List

最新推荐文章于 2024-08-25 16:11:27 发布

jialuyyy

最新推荐文章于 2024-08-25 16:11:27 发布

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本文介绍了一种方法，通过递归遍历二叉树并将节点的右指针指向下一个节点来实现二叉树的扁平化，最终形成一个链表结构。

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Flatten Binary Tree to Linked List

Given a binary tree, flatten it to a linked list in-place.

For example,
Given

The flattened tree should look like:

click to show hints.

Hints:

If you notice carefully in the flattened tree, each node's right child points to the next node of a pre-order traversal.

The hints have stated clearly that each node's right child points to the next node of the pre-order traversal.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    TreeNode lastNode = null;
    public void flatten(TreeNode root) {
        if (root == null)
            return;
        
        if (lastNode != null) {
            lastNode.left = null;
            lastNode.right = root;
        }
        
        lastNode = root;
        TreeNode right = root.right;
        flatten(root.left);
        flatten(right);
        
    }
}