lintcode binary-tree-serialization 二叉树的序列化与反序列化

问题描述

参考

笔记

先序遍历

使用"#"来表示NULL

代码

/**
* Definition of TreeNode:
* class TreeNode {
* public:
*     int val;
*     TreeNode *left, *right;
*     TreeNode(int val) {
*         this->val = val;
*         this->left = this->right = NULL;
*     }
* }
*/
class Solution {
public:
/**
* This method will be invoked first, you should design your own algorithm
* to serialize a binary tree which denote by a root node to a string which
* can be easily deserialized by your own "deserialize" method later.
*/
string serialize(TreeNode *root) {
// write your code here
string s = "";
writeTree(s, root);
return s;
}

void writeTree(string &s, TreeNode* root)
{
if (root == NULL)
{
s += "# ";
return;
}
s += (to_string(root->val) + ' ');
writeTree(s, root->left);
writeTree(s, root->right);
}

/**
* This method will be invoked second, the argument data is what exactly
* you serialized at method "serialize", that means the data is not given by
* system, it's given by your own serialize method. So the format of data is
* designed by yourself, and deserialize it here as you serialize it in
* "serialize" method.
*/
TreeNode *deserialize(string data) {
// write your code here
int pos = 0;
return readTree(data, pos);

}

TreeNode* readTree(string data, int& pos)
{
if (data[pos] == '#')
{
pos += 2;
return NULL;
}
int nownum = 0;
while (data[pos] != ' ')
{
nownum = nownum * 10 + (data[pos] - '0');
pos++;
}
pos++;
TreeNode* nowNode = new TreeNode(nownum);
nowNode->left = readTree(data, pos);
nowNode->right = readTree(data, pos);
return nowNode;
}
};