LeetCode Flatten Binary Tree to Linked List

最新推荐文章于 2022-09-06 16:04:14 发布

kassical

最新推荐文章于 2022-09-06 16:04:14 发布

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分类专栏： LeetCode 文章标签： leetcode 二叉树前序遍历

本文链接：https://blog.youkuaiyun.com/kassical/article/details/38521493

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本文介绍了一种将二叉树结构通过特定算法展平为链表的方法。通过预序遍历的方式，每个节点的右子节点指向预序遍历的下一个节点，最终形成链表结构。

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.

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
	TreeNode *pTreeNode;

	void flatten(TreeNode *root) {
		pTreeNode = NULL;
		preorder(root);
	}

	void preorder(TreeNode *root) {
		if (root == NULL)
			return;

		TreeNode *pLnode = root->left;
		TreeNode *pRnode = root->right;
		if (pTreeNode == NULL) {
			root->left = NULL;
			pTreeNode = root; 
		}
		else {
			root->left = NULL;
			pTreeNode->right = root;
			pTreeNode = root;
		}
		preorder(pLnode);
		preorder(pRnode);
	}
};