贪心法 求解背包问题

实验三：贪心法求解背包问题

一、实验目的与要求

1、掌握背包问题的算法

2、初步掌握贪心算法

二、实验题

问题描述：与0-1背包问题相似，给定n种物品和一个背包。物品i的重量是wi，其价值为vi，背包的容量为c。与0-1背包问题不同的是，在选择物品i装入背包时，背包问题的解决可以选择物品i的一部分，而不一定要全部装入背包，1< i < n。

三、实验代码

package xp3;

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

public class Greedy extends JFrame {

private static final long serialVersionUID= -1508220487443708466L;

private static final int width = 360;// 面板的宽度

private static final int height = 300;// 面板的高度

public int M;

public int[] w;

public int[] p;

public int length;

Greedy() {

// 初始Frame参数设置

this.setTitle("贪心算法");

setDefaultCloseOperation(EXIT_ON_CLOSE);

setSize(width, height);

Container c = getContentPane();

c.setLayout(new BoxLayout(c, BoxLayout.Y_AXIS));

setLocation(350, 150);

// 声明一些字体样式

Font topF1 = new Font("宋体", Font.BOLD, 28);

Font black15 = new Font("宋体", Font.PLAIN, 20);

Font bold10 = new Font("宋体", Font.BOLD, 15);

// 声明工具栏及属性设置

JPanel barPanel = new JPanel();

JMenuBar topBar = new JMenuBar();

topBar.setLocation(1, 1);

barPanel.add(topBar);

// 面板1和顶部标签属性设置

JPanel p1 = new JPanel();

JLabel topLabel = new JLabel("背包问题");

topLabel.setForeground(Color.blue);

topLabel.setFont(topF1);

p1.add(topLabel);

// 中间面板和标签及输入框属性设置

JPanel p2 = new JPanel();

p2.setLayout(new BoxLayout(p2, BoxLayout.Y_AXIS));

JLabel wLabel = new JLabel("重量:");

JLabel pLabel = new JLabel("效益:");

wLabel.setFont(black15);

pLabel.setFont(black15);

//

final JTextField wText = new JTextField(8);

final JTextField pText = new JTextField(8);

p2.add(wLabel);

p2.add(wText);

p2.add(pLabel);

p2.add(pText);

//

// 中下部面板和标签属性设置

JPanel p3 = new JPanel();

JLabel bottomLabel = new JLabel("注意：输入多个时请添加分割符‘,’"); bottomLabel.setFont(bold10);

bottomLabel.setForeground(Color.red);

bottomLabel.setHorizontalAlignment(SwingConstants.RIGHT);

p3.add(bottomLabel);

JPanel p5 = new JPanel();

p5.setLayout(new BoxLayout(p5, BoxLayout.Y_AXIS));

JLabel mLabel = new JLabel(" 背包总重量:");

mLabel.setFont(black15);

final JTextField mText = new JTextField(8);

p5.add(mLabel);

p5.add(mText);

// 面板和按钮的设置

JPanel p4 = new JPanel();

JButton submit = new JButton("确定");

submit.addActionListener(new ActionListener() {

public void actionPerformed(ActionEvent e) {

String s1 = pText.getText(); //效益

String s2 = wText.getText(); //重量

String s3 = mText.getText(); //背包

System.out.println(s1);

System.out.println(s2);

System.out.println(s3);

String s1Copy,s2Copy,s3Copy;

s1Copy = s1;

s2Copy = s2;

s3Copy = s3;

s1Copy = s1Copy.replaceAll(",","");

s2Copy = s2Copy.replaceAll(",","");

s3Copy = s3Copy.replaceAll(",","");

System.out.println(s1Copy);

System.out.println(s2Copy);

System.out.println(s3Copy);

try{

String[] temp = s1.split(",");// 按照‘,’分割字符串

p = new int[temp.length];

for (int i = 0; i < temp.length; i++)

p[i] = Integer.parseInt(temp[i]);//

temp = s2.split(",");

w = new int[temp.length];

for (int i = 0; i < temp.length; i++) w[i] =

Integer.parseInt(temp[i]);//

if (w.length == p.length)

{

length = w.length;

}

else {

JOptionPane.showMessageDialog(null, "长度不等，检查后重新输入！"); }