297. Serialization and deserialization of binary trees

Difficulty 766
Serialization is the operation of converting a data structure or object into consecutive bits , Then the transformed data can be stored in a file or memory , It can also be transmitted to another computer environment through the network , Reconstruct the original data in the opposite way .
Please design an algorithm to realize the serialization and deserialization of binary tree . There's no limit to your sequence / Deserialization algorithm execution logic , You just need to make sure that a binary tree can be serialized into a string and that the string can be deserialized into the original tree structure .
Tips : Input output format and LeetCode The current usage is consistent , Please refer to LeetCode The format of serializing binary tree . You don't have to do this , You can also use other methods to solve this problem .

 Example  1：

 Input ：root = [1,2,3,null,null,4,5] Output ：[1,2,3,null,null,4,5]
 Example  2：
 Input ：root = [] Output ：[]
 Example  3：
 Input ：root = [1] Output ：[1]
 Example  4：
 Input ：root = [1,2] Output ：[1,2]

Tips ：

• The number of nodes in the tree is in the range [0, 104] Inside
• -1000 <= Node.val <= 1000

* Ideas

• Serialization follows the normal idea of traversing the tree , Supplemented by records
• The key to deserialization , Or recursion
  • After root assignment , Recursive left and right subtrees
• Numbers , Strings are passed through stoi,getline,to_string Wait for the function to complete

Code

/** * 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:
    TreeNode* buildTree(queue<string>& q){
            
        if(q.front()=="X"){
    
            q.pop();
            return NULL;
        }
            
        TreeNode* root=new TreeNode( stoi(q.front()) );// Restore string to number 
        q.pop();
        root->left=buildTree(q);
        root->right=buildTree(q);

        return root;
    }

    // Encodes a tree to a single string.
    string serialize(TreeNode* root) {
    // Serialization is obtained by pre ordering , Serialization is separated by spaces 
        if(root==NULL){
    
            return "X ";
        } 
        string dat=to_string(root->val)+' ';

        dat+=serialize(root->left);
        dat+=serialize(root->right);
        return dat;
    }
    // Decodes your encoded data to tree.
    TreeNode* deserialize(string data) {
    
        stringstream str(data);// Pass the string into the input stream ,getline( Input stream , character string , Spacer )
        string node_val;
        queue<string> q;
        while (getline(str, node_val, ' '))// Extract each node 
            q.push(node_val);
        TreeNode* root=buildTree(q);
        return root;
    }

};

// Your Codec object will be instantiated and called as such:
// Codec ser, deser;
// TreeNode* ans = deser.deserialize(ser.serialize(root));