static class File implements Comparable<File> {

String name, head, tail;

int number, idx;

public File(String name, String head, int number, String tail, int idx) {

this.name = name;

this.head = head;

this.number = number;

this.tail = tail;

this.idx = idx;

}

@Override

public int compareTo(File other) {

if(this.head.equals(other.head)) {

if(this.number == other.number) {

// 3) 입력 순(인덱스)

return this.idx - other.idx;

}

// 2) 숫자 순

return this.number - other.number;

}

// 1) head 사전순

return this.head.compareTo(other.head);

}

}

public String[] solution(String[] files) {

List<File> fList = new ArrayList<>();

for(int n=0; n <files.length; n++) {

String file = files[n];

StringBuilder head = new StringBuilder();

StringBuilder number = new StringBuilder();

StringBuilder tail = new StringBuilder();

boolean isHead = false;

boolean isNumber = false;

for(int i=0; i<file.length(); i++) {

char c = file.charAt(i);

if(isHead && isNumber) {

tail.append(c);

continue;

}

if(Character.isDigit(c)) {

isHead = true;

if(number.length() == 5) {

isNumber = true;

tail.append(c);

continue;

}

number.append(c);

} else if(isHead) {

isNumber = true;

tail.append(c);

} else{

head.append(c);

}

}

// File 객체 생성

fList.add(new File(file, head.toString().toUpperCase(), Integer.parseInt(number.toString()), tail.toString(), n));

}

Collections.sort(fList);

String[] answer = new String[fList.size()];

for(int i=0; i<fList.size(); i++) {

File f = fList.get(i);

answer[i] = f.name;

}

return answer;

}

}