class Solution {

public:

/*

* @param strs: a list of strings

* @return: encodes a list of strings to a single string.

*/

string encode(vector<string> &strs) {

// write your code here

string code;

for(const string& s : strs){

code += to_string(s.size()) + ":" + s;

}

return code;

}

/*

* @param str: A string

* @return: decodes a single string to a list of strings

*/

vector<string> decode(string &str) {

// write your code here

vector<string> result;

int i;

while(i < str.size()){

int j = i;

while(str[j] != ':')

j++;

int len = stoi(str.substr(i, j - i);

string word = str.substr(j + 1, len);

result.push_back(word);

i = j + 1 + len;

}

return result;

}

};