标签：style blog http color io os ar for sp
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
If you notice carefully in the flattened tree, each node‘s right child points to the next node of a pre-order traversal.
题意：把一棵二叉树变为链表，要求原地进行转变。
思路：dfs
可以注意到，在链表表示中，每个节点的下一个节点是二叉树的先序遍历中的下一个节点，所以问题就转换为先序遍历了。
复杂度：时间O(n)，空间O(log n)
TreeNode *cur;
void flatten(TreeNode *root) {
if(!root) return;
TreeNode *left = root->left;
TreeNode *right = root->right;
if(cur){
cur->left = NULL;
cur->right = root;
}
cur = root;
flatten(left);
flatten(right);
}
leetcode dfs Flatten Binary Tree to Linked List
标签：style blog http color io os ar for sp
原文地址：http://blog.csdn.net/zhengsenlie/article/details/39997797
