剑指offer | 训练题60：序列化二叉树

题目描述

请实现两个函数，分别用来序列化和反序列化二叉树

思路

//用递归/*struct TreeNode {    int val;    struct TreeNode *left;    struct TreeNode *right;    TreeNode(int x) :            val(x), left(NULL), right(NULL) {    }};*/class Solution {public:        TreeNode* decode(char *&str) {        if(*str == '#'){            str++;            return NULL;        }        int num = 0;        while(*str != ',')            num = num*10 +(*(str++)-'0');//取出一个节点的数字        str++;//删除一个字符','        TreeNode *root = new TreeNode(num);//算出节点总数量        root->left = decode(str);        root->right = decode(str);        return root;    }    char* Serialize(TreeNode *root) {         if(root == NULL) return "#";        string r = to_string(root->val);        r.push_back(',');        //用递归的方法遍历左子树和右子树        char *left = Serialize(root->left);        char *right = Serialize(root->right);        char *ret = new char[strlen(left) + strlen(right) + r.size()];        //得到的字符串拼接起来        strcpy(ret, r.c_str());        strcat(ret, left);        strcat(ret, right);        return ret;    }    TreeNode* Deserialize(char *str) {        return decode(str);    }};