Data commit

Task/Stern-Brocot-sequence/Java/stern-brocot-sequence-1.java

@@ -0,0 +1,34 @@
+import java.math.BigInteger;
+import java.util.LinkedList;
+
+public class SternBrocot {
+	static LinkedList<Integer> sequence = new LinkedList<Integer>(){{
+		add(1); add(1);
+	}};
+	
+	private static void genSeq(int n){
+		for(int conIdx = 1; sequence.size() < n; conIdx++){
+			int consider = sequence.get(conIdx);
+			int pre = sequence.get(conIdx - 1);
+			sequence.add(consider + pre);
+			sequence.add(consider);
+		}
+		
+	}
+	
+	public static void main(String[] args){
+		genSeq(1200);
+		System.out.println("The first 15 elements are: " + sequence.subList(0, 15));
+		for(int i = 1; i <= 10; i++){
+			System.out.println("First occurrence of " + i + " is at " + (sequence.indexOf(i) + 1));
+		}
+		
+		System.out.println("First occurrence of 100 is at " + (sequence.indexOf(100) + 1));
+		
+		boolean failure = false;
+		for(int i = 0; i < 999; i++){
+			failure |= !BigInteger.valueOf(sequence.get(i)).gcd(BigInteger.valueOf(sequence.get(i + 1))).equals(BigInteger.ONE);
+		}
+		System.out.println("All GCDs are" + (failure ? " not" : "") + " 1");
+	}
+}

Task/Stern-Brocot-sequence/Java/stern-brocot-sequence-2.java

@@ -0,0 +1,63 @@
+import java.awt.*;
+import javax.swing.*;
+
+public class SternBrocot extends JPanel {
+
+    public SternBrocot() {
+        setPreferredSize(new Dimension(800, 500));
+        setFont(new Font("Arial", Font.PLAIN, 18));
+        setBackground(Color.white);
+    }
+
+    private void drawTree(int n1, int d1, int n2, int d2,
+            int x, int y, int gap, int lvl, Graphics2D g) {
+
+        if (lvl == 0)
+            return;
+
+        // mediant
+        int numer = n1 + n2;
+        int denom = d1 + d2;
+
+        if (lvl > 1) {
+            g.drawLine(x + 5, y + 4, x - gap + 5, y + 124);
+            g.drawLine(x + 5, y + 4, x + gap + 5, y + 124);
+        }
+
+        g.setColor(getBackground());
+        g.fillRect(x - 10, y - 15, 35, 40);
+
+        g.setColor(getForeground());
+        g.drawString(String.valueOf(numer), x, y);
+        g.drawString("_", x, y + 2);
+        g.drawString(String.valueOf(denom), x, y + 22);
+
+        drawTree(n1, d1, numer, denom, x - gap, y + 120, gap / 2, lvl - 1, g);
+        drawTree(numer, denom, n2, d2, x + gap, y + 120, gap / 2, lvl - 1, g);
+    }
+
+    @Override
+    public void paintComponent(Graphics gg) {
+        super.paintComponent(gg);
+        Graphics2D g = (Graphics2D) gg;
+        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
+                RenderingHints.VALUE_ANTIALIAS_ON);
+
+        int w = getWidth();
+
+        drawTree(0, 1, 1, 0, w / 2, 50, w / 4, 4, g);
+    }
+
+    public static void main(String[] args) {
+        SwingUtilities.invokeLater(() -> {
+            JFrame f = new JFrame();
+            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            f.setTitle("Stern-Brocot Tree");
+            f.setResizable(false);
+            f.add(new SternBrocot(), BorderLayout.CENTER);
+            f.pack();
+            f.setLocationRelativeTo(null);
+            f.setVisible(true);
+        });
+    }
+}