leetcode

• 序列化

  string serialize(TreeNode* root){
      string res;
      dfs_s(root, res);
      return res;
  }
  
  void dfs_s(TreeNode* root, string &res)
  {
      if(!root)
      {
          res += "#,";
          return;
      }
      res += to_string(root -> val) + ',';
      dfs_s(root -> left, res);
      dfs_s(root -> right, res);
  }
  

• 反序列化

  TreeNode* deserialize(string data) {
      int u = 0;
      return dfs_d(data, u);
  }
  
  TreeNode* dfs_d(string data, int &u)
  {
      if(data[u] == '#')
      {
          u += 2;
          return nullptr;
      }
      int t = 0;
      bool is_minus = false;
      while(data[u] != ',')
      {
          if(data[u] == '-') is_minus = true;
          else t = t * 10 + data[u] - '0';
          u ++;
      }
      u ++;
      if(is_minus) t = -t;
      auto root = new TreeNode(t);
      root -> left = dfs_d(data, u);
      root -> right = dfs_d(data, u);
      return root;
  }