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) {

StringBuilder sb = new StringBuilder();

for (String s : strs) {

sb.append(s.length()).append('#').append(s);

}

return sb.toString();

}

/*

* @param str: A single encoded string

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

*/

public List<String> decode(String str) {

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

int i = 0;

while (i < str.length()) {

int j = i;

while (str.charAt(j) != '#') {

j++;

}

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

j++;

result.add(str.substring(j, j + length));

i = j + length;

}

return result;

}

}