[leetcode]449. Serialize and Deserialize BST
[leetcode]449. Serialize and Deserialize BST
Analysis
唉 感覺應該GG了,還是好好刷題看論文吧—— [每天刷題並不難0.0]
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 search tree. There is no restriction on how your serialization/deserialization algorithm should work. You just need to ensure that a binary search tree can be serialized to a string and this string can be deserialized to the original tree structure.
The encoded string should be as compact as possible.
Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.
二叉樹的解碼和編碼,解碼的話就是用preOrder把所有節點值儲存起來,編碼的話就是反過來
Implement
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Codec {
public:
// Encodes a tree to a single string.
string serialize(TreeNode* root) {
string tree = "";
preOrder(tree, root);
return tree;
}
void preOrder(string& tree, TreeNode* node){
if(node == NULL)
return ;
tree += to_string(node->val)+",";
preOrder(tree, node->left) ;
preOrder(tree, node->right);
}
// Decodes your encoded data to tree.
TreeNode* deserialize(string data) {
if(data == "")
return NULL;
vector<string> val1;
string tmp = "";
for(int i=0; i<data.size(); i++){
if(data[i] == ','){
val1.push_back(tmp);
tmp = "";
}
else
tmp += data[i];
}
queue<int> q_val;
for(string v:val1)
q_val.push(stoi(v));
return build(q_val, INT_MIN, INT_MAX);
}
TreeNode* build(queue<int>& q, int low, int up){
if(q.empty())
return NULL;
int vv = q.front();
if(vv < low || vv > up)
return NULL;
q.pop();
TreeNode* root = new TreeNode(vv);
root->left = build(q, low, vv);
root->right = build(q, vv, up);
return root;
}
};
// Your Codec object will be instantiated and called as such:
// Codec codec;
// codec.deserialize(codec.serialize(root));