2016 Update

Task/Ulam-spiral--for-primes-/Java/ulam-spiral--for-primes--2.java

@@ -0,0 +1,67 @@
+import java.awt.*;
+import javax.swing.*;
+
+public class LargeUlamSpiral extends JPanel {
+
+    public LargeUlamSpiral() {
+        setPreferredSize(new Dimension(605, 605));
+        setBackground(Color.white);
+    }
+
+    private boolean isPrime(int n) {
+        if (n <= 2 || n % 2 == 0)
+            return n == 2;
+        for (int i = 3; i * i <= n; i += 2)
+            if (n % i == 0)
+                return false;
+        return true;
+    }
+
+    @Override
+    public void paintComponent(Graphics gg) {
+        super.paintComponent(gg);
+        Graphics2D g = (Graphics2D) gg;
+        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
+                RenderingHints.VALUE_ANTIALIAS_ON);
+
+        g.setColor(getForeground());
+
+        double angle = 0.0;
+        int x = 300, y = 300, dx = 1, dy = 0;
+
+        for (int i = 1, step = 1, turn = 1; i < 40_000; i++) {
+
+            if (isPrime(i))
+                g.fillRect(x, y, 2, 2);
+
+            x += dx * 3;
+            y += dy * 3;
+
+            if (i == turn) {
+
+                angle += 90.0;
+
+                if ((dx == 0 && dy == -1) || (dx == 0 && dy == 1))
+                    step++;
+
+                turn += step;
+
+                dx = (int) Math.cos(Math.toRadians(angle));
+                dy = (int) Math.sin(Math.toRadians(-angle));
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        SwingUtilities.invokeLater(() -> {
+            JFrame f = new JFrame();
+            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            f.setTitle("Large Ulam Spiral");
+            f.setResizable(false);
+            f.add(new LargeUlamSpiral(), BorderLayout.CENTER);
+            f.pack();
+            f.setLocationRelativeTo(null);
+            f.setVisible(true);
+        });
+    }
+}

Task/Ulam-spiral--for-primes-/Java/ulam-spiral--for-primes--3.java

@@ -0,0 +1,79 @@
+import java.awt.*;
+import javax.swing.*;
+
+public class UlamSpiral extends JPanel {
+
+    Font primeFont = new Font("Arial", Font.BOLD, 20);
+    Font compositeFont = new Font("Arial", Font.PLAIN, 16);
+
+    public UlamSpiral() {
+        setPreferredSize(new Dimension(640, 640));
+        setBackground(Color.white);
+    }
+
+    private boolean isPrime(int n) {
+        if (n <= 2 || n % 2 == 0)
+            return n == 2;
+        for (int i = 3; i * i <= n; i += 2)
+            if (n % i == 0)
+                return false;
+        return true;
+    }
+
+    @Override
+    public void paintComponent(Graphics gg) {
+        super.paintComponent(gg);
+        Graphics2D g = (Graphics2D) gg;
+        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
+                RenderingHints.VALUE_ANTIALIAS_ON);
+
+        g.setStroke(new BasicStroke(2));
+
+        double angle = 0.0;
+        int x = 280, y = 330, dx = 1, dy = 0;
+
+        g.setColor(getForeground());
+        g.drawLine(x, y - 5, x + 50, y - 5);
+
+        for (int i = 1, step = 1, turn = 1; i < 100; i++) {
+
+            g.setColor(getBackground());
+            g.fillRect(x - 5, y - 20, 30, 30);
+            g.setColor(getForeground());
+            g.setFont(isPrime(i) ? primeFont : compositeFont);
+            g.drawString(String.valueOf(i), x + (i < 10 ? 4 : 0), y);
+
+            x += dx * 50;
+            y += dy * 50;
+
+            if (i == turn) {
+                angle += 90.0;
+
+                if ((dx == 0 && dy == -1) || (dx == 0 && dy == 1))
+                    step++;
+
+                turn += step;
+
+                dx = (int) Math.cos(Math.toRadians(angle));
+                dy = (int) Math.sin(Math.toRadians(-angle));
+
+                g.translate(9, -5);
+                g.drawLine(x, y, x + dx * step * 50, y + dy * step * 50);
+                g.translate(-9, 5);
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        SwingUtilities.invokeLater(() -> {
+            JFrame f = new JFrame();
+            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            f.setTitle("Ulam Spiral");
+            f.setResizable(false);
+            f.add(new UlamSpiral(), BorderLayout.CENTER);
+            f.pack();
+            f.setLocationRelativeTo(null);
+            f.setVisible(true);
+        });
+    }
+}