JZ37 序列化二叉树

/*
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
    TreeNode(int x) :
            val(x), left(NULL), right(NULL) {
    }
};
*/
class Solution {
public:
    char* Serialize(TreeNode *root) {    
         if(!root) {
             return "#";
         }
        string res = to_string(root->val);
        res.push_back(',');
        
        char* left = Serialize(root->left);
        char* right = Serialize(root->right);
        
        char* ret = new char[strlen(left) + strlen(right) + res.size()];
        
        strcpy(ret, res.c_str());
        strcat(ret, left);
        strcat(ret, right);
        return ret;
    }
    TreeNode* reb (char *&s) {
        if (*s == '#') {
            s++;
            return NULL;
        }
        int num = 0;
        while (*s != ',') {
            num = num * 10 + (*s - '0');
            s ++;
        }
        s ++;
        TreeNode* root = new TreeNode(num);
        root->left = reb(s);
        root->right = reb(s);
        return root;
    }
    TreeNode* Deserialize(char *str) {
        return reb(str);
    }
};

先先序遍历保存下来，然后先序遍历恢复。长的一样