Leetcode题目:Flatten Binary Tree to Linked List
题目:
Given a binary tree, flatten it to a linked list in-place.
For example,
Given
1 / \ 2 5 / \ \ 3 4 6
The flattened tree should look like:
1 \ 2 \ 3 \ 4 \ 5 \ 6
题目解答:
这个题目是将一个二叉树变成一个通过右子节点链接的链表。可以发现的是,变化后右子树整体都在左子树的后面。所以可以先变头,再变左,再变右。我们需要把右子树给暂存起来。
在处理完当前的根节点之后,把左子树链在右边,再接着依次处理它的右节点。
代码:
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: void flatten(TreeNode* root) { TreeNode *curNode = root; while(curNode != NULL) { TreeNode *pre = curNode -> left; TreeNode *tmp = curNode -> right; curNode -> left = NULL; if(pre != NULL) { curNode -> right = pre; while(pre -> right != NULL) { pre = pre -> right; } pre -> right = tmp; } curNode = curNode -> right; } } };