Leetcode 114.二叉树展开为链表

二叉树展开为链表

给定一个二叉树，原地将它展开为链表。

例如，给定二叉树

将其展开为：

class Solution{
public:
    void flatten(TreeNode* root){
        if (root == NULL) return;
        flatten(root->left);
        flatten(root->right);
        TreeNode *temp = root->right;
        root->right = root->left;
        root->left = NULL;
        while (root->right) root = root->right;
        root->right = temp;
    }
}