449. Serialize and Deserialize BST

Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.

Design an algorithm to serialize and deserialize a binary search tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary search tree can be serialized to a string and this string can be deserialized to the original tree structure.

The encoded string should be as compact as possible.

Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.

/**
 * 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) {
        if(!root) return "";
        string order;
        inorderDFS(root, order);
        cout<<order<<endl;
        return order;
    }
     
    inline void inorderDFS(TreeNode* root, string& order) {
        if(!root) return;
        char buf[4];
        memcpy(buf, &(root->val), sizeof(root->val));
        for(int i=0; i<4; i++) order.push_back(buf[i]);
        inorderDFS(root->left, order);
        inorderDFS(root->right, order);
    }
    // Decodes your encoded data to tree.
    TreeNode* deserialize(string data) {
        int pos = 0;
        return reconstruct(data, pos, INT_MIN, INT_MAX);
    }
    
    inline TreeNode* reconstruct(const string& buffer, int& pos, int minValue, int maxValue) {
        if(pos>=buffer.size()) return NULL;
        int val;
        memcpy(&val, &buffer[pos], sizeof(int));
        if(val<minValue || val> maxValue) return NULL;
        
        TreeNode * root = new TreeNode(val);
        pos += sizeof(int);
        root->left = reconstruct(buffer, pos, minValue, val);
        root->right = reconstruct(buffer, pos, val, maxValue);
        return root;
        
    }
};

// Your Codec object will be instantiated and called as such:
// Codec codec;
// codec.deserialize(codec.serialize(root));