/** * post ID : 2380194 * https://www.sololearn.com/Discuss/2380194/grades-average **/ import java.util.ArrayList; import java.util.List; import java.util.Scanner; public class Subject { private final String name; private final int code; private final List grades = new ArrayList<>(); public Subject(final String name, final int code) { this.name = name; this.code = code; } public Subject(final String name, final int code, final int grade) { this.name = name; this.code = code; this.grades.add(grade); } public void addGrade(final int grade) { this.grades.add(grade); } public List getGrades() { return this.grades; } public String getName() { return this.name; } public int getCode() { return this.code; } } public class Student { private final String name; private final int code; private final List subjects = new ArrayList<>(); public Student(final String name, final int code) { this.name = name; this.code = code; } public void addSubject(final Subject subject) { this.subjects.add(subject); } public List getSubjects() { return this.subjects; } public String getName() { return this.name; } public int getCode() { return this.code; } } public class Program { public static void main(final String[] args) { /* sample input 1, student1 2, student2 3, student3 nextfile 1, math 2, physics 3, geography nextfile 18.06.2020, 3 1, 1, 5 1, 2, 5 1, 3, 5 2, 1, 7 2, 2, 7 2, 3, 7 3, 1, 10 3, 2, 10 3, 3, 10 19.06.2020, 2 1, 1, 7 1, 2, 7 1, 3, 5 2, 1, 5 2, 2, 7 2, 3, 7 3, 1, 2 3, 2, 4 3, 3, 6 */ final Scanner sc = new Scanner(System.in); final List students = new ArrayList<>(); // parse students file until "nextfile" (simulates EOF) while (sc.hasNext()) { final String line = sc.nextLine().trim(); if (line.equals("nextfile")) { break; } final String[] values = line.replace(" ", "").split(","); students.add(new Student(values[1], Integer.valueOf(values[0]))); } final List subjects = new ArrayList<>(); // parse subjects file until "nextfile" (simulates EOF) while (sc.hasNext()) { final String line = sc.nextLine().trim(); if (line.equals("nextfile")) { break; } final String[] values = line.replace(" ", "").split(","); subjects.add(new Subject(values[1], Integer.valueOf(values[0]))); } // parse grades file until no more input follows while (sc.hasNext()) { final String line = sc.nextLine().trim(); final String[] values = line.replace(" ", "").split(","); if (values.length > 2) { // only records with values, skip date lines // for each line search student for (Student student : students) { if (student.getCode() == Integer.valueOf(values[0])) { boolean newSubject = true; // find already existing subject to add grade for (Subject subject : student.getSubjects()) { if (subject.getCode() == Integer.valueOf(values[1])) { subject.getGrades().add(Integer.valueOf(values[2])); newSubject = false; } } // first grade in the regarding subject of this student if (newSubject) { for (Subject subject : subjects) { if (subject.getCode() == Integer.valueOf(values[1])) { student.addSubject(new Subject(subject.getName(), subject.getCode(), Integer.valueOf(values[2]))); } } } } } } } // parsed all data for (Student student : students) { for (Subject subject : student.getSubjects()) { int sum = 0; int number = 0; for (Integer grade : subject.getGrades()) { ++number; sum += grade; } if (number > 0) { pr("Student " + student.getName() + " has an average grade of " + (sum / number) + " in subject " + subject.getName()); } } } } public static void pr(final Object obj) { System.out.println(obj); } }

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