SERIALIZE_AND_DESERIALIZE_AND_BINARY_TREE

/**
 * 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:
    string encoded = "";
    string inordered = "";

    void preorder(TreeNode* node) {
        if(node == NULL) {
            encoded += "NULL,";
            return ;
        }
        encoded += to_string(node->val) + ",";

        preorder(node -> left);
        preorder(node -> right);

    }
    // 1,2,NULL,NULL,3,4,NULL,NULL,5,NULL,NULL,

    // Encodes a tree to a single string.
    string serialize(TreeNode* root) {
        preorder(root);
        // cout << encoded << " ";
        return encoded;
    }

    queue<string> preprocess(string data) {
        string str = "";
        queue<string> q;

        for(int i = 0; i < data.size(); ++i) {

            if(data[i] == ',') {
                q.push(str);
                str = "";
            }
            else {
                str+= data[i];
            }
        }

        return q;
    }

    TreeNode* construct(queue<string> &q) {
        string str = q.front();
        q.pop();

        if(str == "NULL") {
            return NULL;
        }

        TreeNode* node = new TreeNode(stoi(str));
        node -> left = construct(q);
        node -> right = construct(q);

        return node;
    }

    // Decodes your encoded data to tree.
    TreeNode* deserialize(string data) {

        queue<string> q = preprocess(data);



        return construct(q);
    }
};

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