Serialize and Deserialize Binary Tree_Week9
题目:(Serialize and Deserialize Binary Tree) ←链接戳这里
题目说明:
Serialization is the process of converting a data structure or object into a sequence of bits so that it can be stored in a file or memory buffer, or transmitted across a network connection link to be reconstructed later in the same or another computer environment.
Design an algorithm to serialize and deserialize a binary tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary tree can be serialized to a string and this string can be deserialized to the original tree structure.
难度: Hard
解题思路:
题目意为,想办法将二叉树序列化,再根据序列重造二叉树。简单来说就是讲已经做好的树结构用自己定义的顺序(可唯一识别)序列化成一串string,这样可以很方便简单地移动数据。而该string,又可以用方法,将其重造成一棵树。
因为前序是最简单的,所以决定用前序来构造序列,到达空节点时用*号标志,这样可以简单地恢复该树。
class Codec {
public:
string serialize(TreeNode* root) {
//将生成的序列定义为result
string result = "";
//若该节点不是空节点,则加入string,并前序访问子树
if (root != NULL) {
result += root->val + " ";
serialize(root->left);
serialize(root->right);
} else {
//该节点是空节点,用*号标记
result += "* ";
}
return result;
}
// 用换了istringstream参数的函数来分析更方便于是写了个deserialize2函数
TreeNode* deserialize(string data) {
istringstream in(data);
return deserialize2(in);
}
private:
TreeNode* deserialize2(istringstream& in) {
//将in流字符一个个导出成string并且自动无视空格符
string val;
in >> val;
//若标记"*",则表示为空节点
if (val =="*") {
return NULL;
}
//按照前序序列构造树。
TreeNode* root = new TreeNode((int)(val[0] -'0'));
root->left = deserialize2(in);
root->right = deserialize2(in);
return root;
}
};