Notes

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

class Barang {
int kode;
String nama_barang;
int jumlah;
double diskon;
double harga;

public Barang(int kode, String nama_barang, int jumlah, double diskon, double harga) {
this.kode = kode;
this.nama_barang = nama_barang;
this.jumlah = jumlah;
this.diskon = diskon;
this.harga = harga;
}
}

class Node {
Barang barang;
Node next;

public Node(Barang barang) {
this.barang = barang;
this.next = null;
}
}

public class Penjualan {
Node head;

public void tambahSimpul(Barang barang) {
Node new_node = new Node(barang);
if (head == null) {
head = new_node;
head.next = head;
} else {
Node current = head;
Node prev = null;
do {
if (current.barang.nama_barang.compareTo(barang.nama_barang) > 0) {
break;
}
prev = current;
current = current.next;
} while (current != head);

new_node.next = current;
if (prev != null) {
prev.next = new_node;
} else {
Node last = head;
while (last.next != head) {
last = last.next;
}
last.next = new_node;
head = new_node;
}
}
}

public void hapusDiskonNol() {
if (head == null) {
return;
}

Node current = head;
Node prev = null;
Node first = head;

do {
if (current.barang.diskon == 0) {
if (current == head) {
head = current.next;
}
if (prev != null) {
prev.next = current.next;
}
if (current == first) {
first = current.next;
}
} else {
prev = current;
}
current = current.next;
} while (current != first);
}

public double rataRataHarga() {
Node current = head;
double totalHarga = 0;
int count = 0;
do {
totalHarga += (current.barang.harga - (current.barang.diskon / 100) * current.barang.harga) * current.barang.jumlah;
count++;
current = current.next;
} while (current != head);

return count > 0 ? totalHarga / count : 0;
}

public void tampilkanDataDiatasRataRata() {
Node current = head;
double rataRata = rataRataHarga();
do {
double totalHarga = (current.barang.harga - (current.barang.diskon / 100) * current.barang.harga) * current.barang.jumlah;
if (totalHarga > rataRata) {
System.out.println("Kode: " + current.barang.kode + ", Nama Barang: " + current.barang.nama_barang
+ ", Harga: " + current.barang.harga + ", Diskon: " + current.barang.diskon + ", Jumlah: "
+ current.barang.jumlah);
}
current = current.next;
} while (current != head);
}

public double totalHarga() {
Node current = head;
double totalHarga = 0;
do {
totalHarga += (current.barang.harga - (current.barang.diskon / 100) * current.barang.harga) * current.barang.jumlah;
current = current.next;
} while (current != head);
return totalHarga;
}

public static void main(String[] args) {
Penjualan penjualan = new Penjualan();

Barang barang1 = new Barang(1000, "Kalender", 1, 10, 20000);
Barang barang2 = new Barang(1001, "Rak Buku", 20, 60, 50000);
Barang barang3 = new Barang(1002, "Baskom", 100, 0, 1000);

penjualan.tambahSimpul(barang1);
penjualan.tambahSimpul(barang2);
penjualan.tambahSimpul(barang3);

System.out.println("Data sebelum penghapusan diskon 0%:");
penjualan.tampilkanDataDiatasRataRata();

penjualan.hapusDiskonNol();
System.out.println("nData setelah penghapusan diskon 0%:");
penjualan.tampilkanDataDiatasRataRata();

double totalHarga = penjualan.totalHarga();
System.out.println("nTotal Harga: " + totalHarga);
}
}