我的解题
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Codec
{
public:
// Encodes a tree to a single string.
string serialize(TreeNode *root)
{
stringstream ss;
do_serialize(root, ss);
return ss.str();
}
void do_serialize(TreeNode *root, stringstream &ss)
{
if (root)
{
ss << root->val << ",";
do_serialize(root->left, ss);
do_serialize(root->right, ss);
}
else
{
ss << "N" << ",";
}
}
// Decodes your encoded data to tree.
TreeNode* deserialize(string data)
{
list<string> nodes;
string temp;
for (auto &&c : data)
{
if (c == ',')
{
nodes.emplace_back(temp);
temp.clear();
}
else
{
temp.push_back(c);
}
}
return do_deserialize(nodes);
}
TreeNode* do_deserialize(list<string> &nodes)
{
if (nodes.front() == "N")
{
nodes.pop_front();
return nullptr;
}
else
{
int val = stoi(nodes.front());
TreeNode *n = new TreeNode { val };
nodes.pop_front();
n->left = do_deserialize(nodes);
n->right = do_deserialize(nodes);
return n;
}
}
};
// Your Codec object will be instantiated and called as such:
// Codec codec;
// codec.deserialize(codec.serialize(root));