Instruction for the practice problem can be found here: https://ds.cs.rutgers.edu/assignment-ru-kindergarten/

this is mainly about linkedLists.

I need help with a method provided in Classroom.java. The method is insertMusicalChairs()

Note that this method takes students from studentsSitting array and place them into circular linked list (musicalChairs). Then, removes the student from the array.

note: (.next in the SNode class is private and cannot be used to implement the code)

SNode.java

package kindergarten; /** * This class represents a student node, with a student * object representing the student, and a next pointer * for the student next in line. * * @author Ethan Chou */ public class SNode { private Student student; // the data part of the node private SNode next; // a link to the next student int the linked list public SNode ( Student s, SNode n ) { student = s; next = n; } public SNode() { this(null, null); } public Student getStudent () { return student; } public void setStudent (Student s) { student = s; } public SNode getNext () { return next; } public void setNext (SNode n) { next = n; } } 

Student.java

package kindergarten; /** * This class represents a student, with a string variable for the * student's name and an int variable for the student's height. * * @author Ethan Chou */ public class Student { private String firstName; private String lastName; private int height; /* * Constructor */ public Student ( String f, String l, int h ) { firstName = f; lastName = l; height = h; } /* * Default constructor sets student's height to 0 (zero) */ public Student () { this(null, null, 0); } /** * Compares the names of this student to paremeter student, * returning an int value representing which name comes in first alphabetically. * * @param other the student being compared * * @return an int value of which name comes first alphabetically * n < 0 means this student's name comes before parameter student * n > 0 means parameter student's name comes before this student */ public int compareNameTo ( Student other ) { int lastNameCompare = this.lastName.compareToIgnoreCase(other.getLastName()); if ( lastNameCompare == 0 ) { // same last name, compare first names return this.firstName.compareToIgnoreCase(other.getFirstName()); } return lastNameCompare; } /* * Prints the student object */ public String print () { String printName = ""; printName += this.firstName.charAt(0) + ". "; if ( lastName.length() > 4 ) { printName += this.lastName.substring(0, 4); } else { printName += lastName; } return printName; } /* Getter and setter methods */ public String getFirstName () { return firstName; } public void setFirstName ( String f ) { firstName = f; } public String getLastName () { return lastName; } public void setLastName ( String l ) { lastName = l; } public int getHeight () { return height; } public void setHeight ( int h ) { height = h; } public String getFullName () { return this.firstName + " " + this.lastName;} } 

Classroom.java: Method to be updated!

package kindergarten; /** * This class represents a Classroom, with: * - an SNode instance variable for students in line, * - an SNode instance variable for musical chairs, pointing to the last student in the list, * - a boolean array for seating availability (eg. can a student sit in a given seat), and * - a Student array parallel to seatingAvailability to show students filed into seats * --- (more formally, seatingAvailability[i][j] also refers to the same seat in studentsSitting[i][j]) * * @author Ethan Chou * @author Kal Pandit * @author Maksims Kurjanovics Kravcenko */ public class Classroom { private SNode studentsInLine; // when students are in line: references the FIRST student in the LL private SNode musicalChairs; // when students are in musical chairs: references the LAST student in the CLL private boolean[][] seatingLocation; // represents the classroom seats that are available to students private Student[][] studentsSitting; // when students are sitting in the classroom: contains the students /** * Constructor for classrooms. Do not edit. * @param l passes in students in line * @param m passes in musical chairs * @param a passes in availability * @param s passes in students sitting */ public Classroom ( SNode l, SNode m, boolean[][] a, Student[][] s ) { studentsInLine = l; musicalChairs = m; seatingLocation = a; studentsSitting = s; } /** * Default constructor starts an empty classroom. Do not edit. */ public Classroom() { this(null, null, null, null); } /** * This method simulates students standing in line and coming into the classroom (not leaving the line). * * It does this by reading students from input file and inserting these students studentsInLine singly linked list. * * 1. Open the file using StdIn.setFile(filename); * * 2. For each line of the input file: * 1. read a student from the file * 2. make an object of type Student with the student information * 3. insert the Student object at the FRONT of the linked list * * Input file has: * 1) one line containing an integer representing the number of students in the file, say x * 2) x lines containing one student per line. Each line has the following student * information separated by spaces: FirstName LastName Height * * To read a string using StdIn use StdIn.readString() * * The input file has Students in REVERSE alphabetical order. So, at the end of this * method all students are in line in alphabetical order. * * DO NOT implement a sorting method, PRACTICE add to front. * * @param filename the student information input file */ public void enterClassroom ( String filename ) { //CODE HERE } } /** * * This method creates and initializes the seatingAvailability (2D array) of * available seats inside the classroom. Imagine that unavailable seats are broken and cannot be used. * * 1. Open the file using StdIn.setFile(seatingChart); * * 2. You will read the seating chart input file with the format: * An integer representing the number of rows in the classroom, say r * An integer representing the number of columns in the classroom, say c * Number of r lines, each containing c true or false values (true represents that a * seat is present in that column) * * 3. Initialize seatingLocation and studentsSitting arrays with r rows and c columns * * 4. Update seatingLocation with the boolean values read from the input file * * This method does not seat students on the seats. * * @param seatingChart the seating chart input file */ public void setupSeats(String seatingChart) { // CODE HERE } /** * * This method simulates students standing inline and then taking their seats in the classroom. * * 1. Starting from the front of the studentsInLine singly linked list * 2. Remove one student at a time from the list and insert the student into studentsSitting according to * seatingLocations * * studentsInLine will then be empty * * If the students just played musical chairs, the winner of musical chairs is seated separately * by seatMusicalChairsWinner(). */ public void seatStudents () { // CODE HERE } /** * Traverses studentsSitting row-wise (starting at row 0) removing a seated * student and adding that student to the end of the musicalChairs list. * * row-wise: starts at index [0][0] traverses the entire first row and then moves * into second row. */ public void insertMusicalChairs () { // CODE HERE }