public class Solution {

/*

* @param strs: a list of strings

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

*/

public String encode(List<String> strs) {

// write your code here

StringBuilder sb = new StringBuilder();

for (String str : strs) {

sb.append(str.length()).append("#").append(str);

}

return sb.toString();

}

/*

* @param str: A string

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

*/

public List<String> decode(String str) {

// write your code here

List<String> output = new ArrayList<>();

int i = 0;

while (i < str.length()) {

int idx = str.indexOf('#', i);

int length = Integer.parseInt(str.substring(i, idx));

String s = str.substring(idx + 1, idx + 1 + length);

output.add(s);

i = idx + 1 + length;

}

return output;

}

}