关于100个人随机给钱的模拟实验

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