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.
For example, you may serialize the following tree
1 / 2 3 / 4 5
as "[1,2,3,null,null,4,5]"
, just the same as how LeetCode OJ serializes a binary tree. You do not necessarily need to follow this format, so please be creative and come up with different approaches yourself.
Note: Do not use class member/global/static variables to store states. Your serialize and deserialize algorithms should be stateless.
/** * 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 s = ""; queue<TreeNode*> q; if(root) q.push(root); while(!q.empty()) { TreeNode *p = q.front(); q.pop(); if(!p) { s += "null "; } else { s += to_string(p->val) + " "; q.push(p->left); q.push(p->right); } } cout<<s<<endl; return s; } // Decodes your encoded data to tree. TreeNode* deserialize(string data) { cout<<data<<endl; if(data == "") return NULL; int l = data.length(), idx1 = 0, idx2; queue<TreeNode*> q; TreeNode *root = NULL; bool flag = 0; //0表示该左子树,1表示该右子树 while(idx1 < l) { idx2 = data.find(" ", idx1+1); string s = data.substr(idx1, idx2-idx1); if(s == "null") { if(flag) { q.front()->right = NULL; q.pop(); } else q.front()->left = NULL; flag = !flag; } else { int t = atoi(s.c_str()); TreeNode *p = new TreeNode(t); if(!root) root = p; else { if(flag) { q.front()->right = p; q.pop(); } else q.front()->left = p; flag = !flag; } q.push(p); } idx1 = idx2+1; } return root; } }; // Your Codec object will be instantiated and called as such: // Codec codec; // codec.deserialize(codec.serialize(root));