Encode and Decode Strings -- LeetCode

標籤：

Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings.

Machine 1 (sender) has the function:

string encode(vector<string> strs) {  // ... your code  return encoded_string;}

Machine 2 (receiver) has the function:

vector<string> decode(string s) {  //... your code  return strs;}

So Machine 1 does:

string encoded_string = encode(strs);

and Machine 2 does:

vector<string> strs2 = decode(encoded_string);

strs2 in Machine 2 should be the same as strs in Machine 1.

Implement the encode and decode methods.

Note:

• The string may contain any possible characters out of 256 valid ascii characters. Your algorithm should be generalized enough to work on any possible characters.
• Do not use class member/global/static variables to store states. Your encode and decode algorithms should be stateless.
• Do not rely on any library method such as eval or serialize methods. You should implement your own encode/decode algorithm.

思路：每個字串之前添加它的長度和一個%字元。

 1 class Codec { 2 public: 3  4     // Encodes a list of strings to a single string. 5     string encode(vector<string>& strs) { 6         string res; 7         for (int i = 0; i < strs.size(); i++) 8             res += std::to_string(strs[i].size()) + "%" + strs[i]; 9         return res;10     }11 12     // Decodes a single string to a list of strings.13     vector<string> decode(string s) {14         vector<string> res;15         int curInd = 0;16         int mark = s.find("%");17         while (mark != std::string::npos) {18             int len = std::stoi(s.substr(curInd, mark - curInd));19             if (len) res.push_back(s.substr(mark + 1, len));20             //in case it is an empty string21             else res.push_back("");22             curInd = mark + len + 1;23             mark = s.find("%", curInd);24         }25         return res;26     }27 };28 29 // Your Codec object will be instantiated and called as such:30 // Codec codec;31 // codec.decode(codec.encode(strs));

 

Encode and Decode Strings -- LeetCode