前言
在知乎上看到一个好玩的问题：房间里有100个人，每人都有100元钱，他们在玩一个游戏。每轮游戏中，每个人都要拿出一元钱随机给另一个人，最后这100个人的财富分布是怎样的？
今天使用java中的GUI来模拟一下。
实现
效果图如下
红色表示负债，模拟次数大概150W次。
代码实现
可视化主类
import java.awt.EventQueue;
import java.util.Arrays;
public class AlgoVisualizer {
private static int DELAY = 40;
private int[] money;
private AlgoFrame frame;
public AlgoVisualizer(int sceneWidth, int sceneHeight) {
// 初始化数据
money = new int[100];
for (int i = 0; i < money.length; i++) {
money[i] = 100;
}
// 初始化视图
EventQueue.invokeLater(() -> {
frame = new AlgoFrame("Money Problem", sceneWidth, sceneHeight);
new Thread(this::run).start();
});
}
public void run() {
while (true) {
// 改进2：是否排序
Arrays.sort(money);
frame.render(money);
AlgoVisHelper.pause(DELAY);
// 改进1：每一帧执行的轮数
for (int k = 0; k < 50; k++) {
for (int i = 0; i < money.length; i++) {
// 改进3：允许money为负值
//if(money[i] > 0){
int j = (int) (Math.random() * money.length);
money[i] -= 1;
money[j] += 1;
//}
}
}
}
}
public static void main(String[] args) {
int sceneWidth = 1000;
int sceneHeight = 800;
AlgoVisualizer vis = new AlgoVisualizer(sceneWidth, sceneHeight);
}
}
窗口类
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
* 主窗口
*/
public class AlgoFrame extends JFrame {
private int canvasWidth;
private int canvasHeight;
public AlgoFrame(String title, int canvasWidth, int canvasHeight) {
super(title);
this.canvasWidth = canvasWidth;
this.canvasHeight = canvasHeight;
AlgoCanvas canvas = new AlgoCanvas();
setContentPane(canvas);
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setResizable(false);
setVisible(true);
}
public AlgoFrame(String title) {
this(title, 1024, 768);
}
public int getCanvasWidth() {
return canvasWidth;
}
public int getCanvasHeight() {
return canvasHeight;
}
// data
private int[] money;
public void render(int[] money) {
this.money = money;
repaint();
}
private class AlgoCanvas extends JPanel {
public AlgoCanvas() {
// 双缓存
super(true);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
// 抗锯齿
RenderingHints hints = new RenderingHints(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.addRenderingHints(hints);
// 具体绘制
int w = canvasWidth / money.length;
for (int i = 0; i < money.length; i++) {
if (money[i] > 0) {
AlgoVisHelper.setColor(g2d, AlgoVisHelper.Blue);
AlgoVisHelper.fillRectangle(g2d,
i * w + 1, canvasHeight / 2 - money[i], w - 1, money[i]);
} else {
AlgoVisHelper.setColor(g2d, AlgoVisHelper.Red);
AlgoVisHelper.fillRectangle(g2d,
i * w + 1, canvasHeight / 2, w - 1, -money[i]);
}
}
}
@Override
public Dimension getPreferredSize() {
return new Dimension(canvasWidth, canvasHeight);
}
}
}
工具类
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import javax.swing.ImageIcon;
/**
* 工具类
*/
public class AlgoVisHelper {
private AlgoVisHelper() {
}
public static final Color Red = new Color(0xF44336);
public static final Color Pink = new Color(0xE91E63);
public static final Color Purple = new Color(0x9C27B0);
public static final Color DeepPurple = new Color(0x673AB7);
public static final Color Indigo = new Color(0x3F51B5);
public static final Color Blue = new Color(0x2196F3);
public static final Color LightBlue = new Color(0x03A9F4);
public static final Color Cyan = new Color(0x00BCD4);
public static final Color Teal = new Color(0x009688);
public static final Color Green = new Color(0x4CAF50);
public static final Color LightGreen = new Color(0x8BC34A);
public static final Color Lime = new Color(0xCDDC39);
public static final Color Yellow = new Color(0xFFEB3B);
public static final Color Amber = new Color(0xFFC107);
public static final Color Orange = new Color(0xFF9800);
public static final Color DeepOrange = new Color(0xFF5722);
public static final Color Brown = new Color(0x795548);
public static final Color Grey = new Color(0x9E9E9E);
public static final Color BlueGrey = new Color(0x607D8B);
public static final Color Black = new Color(0x000000);
public static final Color White = new Color(0xFFFFFF);
public static void strokeCircle(Graphics2D g, int x, int y, int r) {
Ellipse2D circle = new Ellipse2D.Double(x - r, y - r, 2 * r, 2 * r);
g.draw(circle);
}
public static void fillCircle(Graphics2D g, int x, int y, int r) {
Ellipse2D circle = new Ellipse2D.Double(x - r, y - r, 2 * r, 2 * r);
g.fill(circle);
}
public static void strokeRectangle(Graphics2D g, int x, int y, int w, int h) {
Rectangle2D rectangle = new Rectangle2D.Double(x, y, w, h);
g.draw(rectangle);
}
public static void fillRectangle(Graphics2D g, int x, int y, int w, int h) {
Rectangle2D rectangle = new Rectangle2D.Double(x, y, w, h);
g.fill(rectangle);
}
public static void setColor(Graphics2D g, Color color) {
g.setColor(color);
}
public static void setStrokeWidth(Graphics2D g, int w) {
int strokeWidth = w;
g.setStroke(new BasicStroke(strokeWidth, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
}
public static void pause(int t) {
try {
Thread.sleep(t);
} catch (InterruptedException e) {
System.out.println("Error sleeping");
}
}
public static void putImage(Graphics2D g, int x, int y, String imageURL) {
ImageIcon icon = new ImageIcon(imageURL);
Image image = icon.getImage();
g.drawImage(image, x, y, null);
}
public static void drawText(Graphics2D g, String text, int centerx, int centery) {
if (text == null) {
throw new IllegalArgumentException("Text is null in drawText function!");
}
FontMetrics metrics = g.getFontMetrics();
int w = metrics.stringWidth(text);
int h = metrics.getDescent();
g.drawString(text, centerx - w / 2, centery + h);
}
}
参考
该如何面对这个残酷的世界？-搜狐财经
关于“房间里有100个人，每人都有100元钱，每轮每人要拿一元钱随机给另一个人”这个游戏的解析解。-知乎
关于100个人随机给钱的模拟实验。-知乎