题目
给定一个二叉树,其中所有的右节点要么是具有兄弟节点(拥有相同父节点的左节点)的叶节点,要么为空,将此二叉树上下翻转并将它变成一棵树, 原来的右节点将转换成左叶节点。返回新的根。
解题思路
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:
TreeNode* upsideDownBinaryTree(TreeNode* root) {
TreeNode * tmp;
TreeNode * resultfromLeft;
if(root == NULL || root->left == NULL) return root;
resultfromLeft = upsideDownBinaryTree(root->left);
tmp = resultfromLeft;
while(tmp->right != NULL) tmp = tmp->right;
tmp->right = root;
tmp->left = root->right;
root->left = root->right = NULL;
return resultfromLeft;
}
};