LeetCode:114_Flatten Binary Tree to Linked List | 将一棵二叉树变成链表的形式 | Medium

 1 struct TreeNode {
 2     int            val;
 3     TreeNode*    left;
 4     TreeNode*    right;
 5     TreeNode(int x): val(x), left(NULL),right(NULL) {}
 6 };
 7 
 8 void flatten(TreeNode *root)
 9 {
10     if (NULL == root)
11         return;
12     //使用stack的非递归方法
13     TreeNode *left = root->left;
14     TreeNode *right = root->right;
15 
16     if (left) {
17         root->right = left;
18         root->left = NULL;
19 
20         TreeNode *pTemp = left;
21         while (pTemp->right)
22             pTemp = pTemp->right;
23         pTemp->right = right;
24 
25         flatten(root->right);
26     }
27 }