简单点吧    几行代码
import java.time.LocalDate;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        String[] s1 = s.split(" ");
        LocalDate nowDate  =LocalDate.of(Integer.valueOf(s1[0]),Integer.valueOf(s1[1]),Integer.valueOf(s1[2]));
        System.out.println(nowDate.getDayOfYear());
    }
}