序列化二叉树

    char* Serialize(TreeNode *root) {
        if(root == NULL)
        {
            char* ch = new char[2];
            ch[0] = ‘%‘;
            ch[1] = ‘\0‘;
            return ch;
        }
        string str ;
        str += to_string(root->val);
        str += ‘,‘;
        str += Serialize(root->left);
        str += Serialize(root->right);
        char *p=  (char*)malloc(str.length()+2);
        str.copy(p, str.length(), 0);
        p[str.length()] = ‘\0‘;
        return p;
    }

char* Serialize(TreeNode *root) {
        if(root == NULL)
            return NULL;
        string str ;
        Serialize(root,str);
        char *p=  (char*)malloc(str.length()+1);
        str.copy(p,str.length(),0);
        p[str.length()] = ‘\0‘;
        return p;
    }
    void Serialize(TreeNode *root,string& str)
    {
        if(root == NULL)
        {
            str += "%";
            return ;
        }
        str += to_string(root->val);
        str += ‘,‘;
        Serialize(root->left,str);
        Serialize(root->right,str);
    }

    TreeNode* Deserialize(char *str) {
        if(str == NULL)
            return NULL;
        return Deserialize(&str);
    }
    TreeNode* Deserialize(char **str) {
        if(**str == ‘%‘)
        {
            (*str)++;
            return NULL;
        }
        int num = 0;
        while(**str != ‘,‘)
        {
            num = num*10 + ((**str) - ‘0‘);
            (*str)++;
        }
        TreeNode* pRoot = new TreeNode(num);
        (*str)++;
        pRoot->left = Deserialize(str);
        pRoot->right = Deserialize(str);
        return pRoot;
    }