import java.util.ArrayList;
import java.util.List;
public class BinaryWatch {
public List readBinaryWatch(int num) {
int[] f = new int[] {
1, 2, 4, 8, 1, 2, 4, 8, 16, 32
};
List list = new ArrayList();
readBinaryWatch(num, f, 0, 0, 0, list);
return list;
}
public void readBinaryWatch(int num, int[] f, int index, int hour, int minute, List list) {
if (num == 0 && hour < 12 && minute < 60) {
list.add(String.format("%d:%02d", hour, minute));
return;
}
if (index >= f.length) {
return;
}
int nextHour = index <= 3 ? hour + f[index] : hour;
int nextMinute = index > 3 ? minute + f[index] : minute;
readBinaryWatch(num - 1, f, index + 1, nextHour, nextMinute, list);
readBinaryWatch(num, f, index + 1, hour, minute, list);
}
}