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
思想： 如 Hints.
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
TreeNode* getPreNode(TreeNode *root) {
if(root == NULL) return NULL;
while(root->right) root = root->right;
return root;
}
class Solution {
public:
void flatten(TreeNode *root) {
if(root == NULL) return;
TreeNode *pre = getPreNode(root->left);
if(pre) {
pre->right = root->right;
root->right = root->left;
root->left = NULL;
}
flatten(root->right);
}
};
31. Flatten Binary Tree to Linked List
原文：http://www.cnblogs.com/liyangguang1988/p/3939660.html