import java.util.*;

public class Codec {

/**

1. complexity:

- time: O(N * L), where N is the length of strs, L is maximum length of each word in strs

- space: O(N * L)

*/

// Encodes a list of strings to a single string.

public String encode(List<String> strs) {

// 필요한 정보: 전체 원본 문자열, 각 단어의 위치와 길이

StringBuilder origin = new StringBuilder();

StringJoiner meta = new StringJoiner("/");

StringJoiner encoded = new StringJoiner(";");

int startIdx = 0;

for (String word: strs) { // O(N)

origin.append(word);

meta.add(String.format("(%d,%d)", startIdx, word.length()));

startIdx += word.length();

}

encoded.add(origin.toString()).add(meta.toString());

return encoded.toString();

}

// Decodes a single string to a list of strings.

public List<String> decode(String s) {

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

int delimeterIdx = s.lastIndexOf(";"); // O(N * L)

String origin = s.substring(0, delimeterIdx); // O(N * L)

String meta = s.substring(delimeterIdx+1); // O(N * L)

String[] wordInfos = meta.split("/");

for (String wordInfo: wordInfos) { // O(N)

delimeterIdx = wordInfo.indexOf(","); // O(1)

int length = Integer.parseInt(wordInfo.substring(delimeterIdx+1, wordInfo.length() - 1)); // O(1)

String word = "";

if (length > 0) {

int startIdx = Integer.parseInt(wordInfo.substring(1, delimeterIdx));

word = origin.substring(startIdx, startIdx + length);

}

ret.add(word);

}

return ret;

}

}

// Your Codec object will be instantiated and called as such:

// Codec codec = new Codec();

// codec.decode(codec.encode(strs));