LeetCode 297. 二叉树的序列化与反序列化（前序遍历层序遍历）

文章目录

- 1. 题目
- 2. 解题
- - 2.1 前序遍历
  - 2.2 层序遍历

1. 题目

序列化是将一个数据结构或者对象转换为连续的比特位的操作，进而可以将转换后的数据存储在一个文件或者内存中，同时也可以通过网络传输到另一个计算机环境，采取相反方式重构得到原数据。

二叉树，字符，互转

《剑指Offer》同题：面试题37. 序列化二叉树
449. 序列化和反序列化二叉搜索树

2. 解题

类似题解：
LeetCode 331. 验证二叉树的前序序列化
LeetCode 428. 序列化和反序列化 N 叉树（DFS）

2.1 前序遍历

class Codec {
public:// Encodes a tree to a single string.string serialize(TreeNode* root) {ostringstream out;serialize(root,out);return out.str();}// Decodes your encoded data to tree.TreeNode* deserialize(string data) {istringstream in(data);return deserialize(in);}
private:void serialize(TreeNode* root,ostringstream &out){if(root){out<< root->val << ' ';serialize(root->left,out);serialize(root->right,out);}elseout << "N ";  }TreeNode* deserialize(istringstream &in){string val;in >> val;if(val == "N"){return NULL;}TreeNode* root = new TreeNode(stoi(val));root->left = deserialize(in);root->right = deserialize(in);return root;}
};

2.2 层序遍历

class Codec {
public:// Encodes a tree to a single string.string serialize(TreeNode* root) {if(root == NULL) return "";queue<TreeNode*> q;TreeNode* node;q.push(root);ostringstream out;while(!q.empty()){node = q.front();q.pop();if(node == NULL)   out << "N ";else{out << node->val << " ";q.push(node->left);q.push(node->right);}}  return out.str();}// Decodes your encoded data to tree.TreeNode* deserialize(string data) {if(data.empty())    return NULL;istringstream in(data);string s;in >> s;TreeNode* root = new TreeNode(stoi(s));	    queue<TreeNode*> q;TreeNode* node;q.push(root);	    while(!q.empty()){node = q.front();q.pop();in >> s;if(s[0] == 'N')node->left = NULL;else{node->left = new TreeNode(stoi(s));q.push(node->left);}in >> s;if(s[0] == 'N')node->right = NULL;else{node->right = new TreeNode(stoi(s));q.push(node->right);}} return root;}
};