【剑指offer】序列化二叉树

 1 /*
 2 struct TreeNode {
 3     int val;
 4     struct TreeNode *left;
 5     struct TreeNode *right;
 6     TreeNode(int x) :
 7             val(x), left(NULL), right(NULL) {
 8     }
 9 };
10 */
11 class Solution {
12 public:
13     char* Serialize(TreeNode *root) {    
14         if(root == NULL)    return NULL;
15         string str;
16         Serialize(root,str);
17         //string转char*字符串
18         int len = str.length();
19         char* ans = new char[len+1];
20         for(int i =0 ; i < len;i++){
21             ans[i] = str[i];
22         }
23         ans[len] = ‘\0‘;
24         return ans;
25     }
26     TreeNode* Deserialize(char* str) {
27         if(str == NULL)    return NULL;
28         TreeNode* ans =  Deserialize(&str);
29         return ans;
30     }
31     
32     void Serialize(TreeNode* root,string& str){
33         if(root == NULL){
34             str += ‘#‘; return;
35         }//指针为空
36         
37         string tmp = to_string(root->val);
38         str += tmp;
39         str +=‘,‘;    //区分每个节点，先序遍历
40         Serialize(root->left,str);
41         Serialize(root->right,str);
42     }
43     //char**的声明很重要。
44      TreeNode* Deserialize(char** str){
45          //到达叶节点
46          if(**str == ‘#‘){
47              (*str)++; return NULL;
48          }
49          //转换字符
50          int num = 0;
51          while(**str != ‘,‘ && **str !=‘\0‘){
52              num = num*10+((**str) - ‘0‘);
53              (*str)++;
54          }
55          //建树
56          TreeNode* root = new TreeNode(num);
57          if(**str ==‘\0‘)    return root;
58          else    (*str)++;
59          root->left = Deserialize(str);
60          root->right = Deserialize(str);
61          return root;
62      }
63 };