Data commit

Task/Peano-curve/Java/peano-curve.java

@@ -0,0 +1,90 @@
+import java.io.*;
+
+public class PeanoCurve {
+    public static void main(final String[] args) {
+        try (Writer writer = new BufferedWriter(new FileWriter("peano_curve.svg"))) {
+            PeanoCurve s = new PeanoCurve(writer);
+            final int length = 8;
+            s.currentAngle = 90;
+            s.currentX = length;
+            s.currentY = length;
+            s.lineLength = length;
+            s.begin(656);
+            s.execute(rewrite(4));
+            s.end();
+        } catch (final Exception ex) {
+            ex.printStackTrace();
+        }
+    }
+
+    private PeanoCurve(final Writer writer) {
+        this.writer = writer;
+    }
+
+    private void begin(final int size) throws IOException {
+        write("<svg xmlns='http://www.w3.org/2000/svg' width='%d' height='%d'>\n", size, size);
+        write("<rect width='100%%' height='100%%' fill='white'/>\n");
+        write("<path stroke-width='1' stroke='black' fill='none' d='");
+    }
+
+    private void end() throws IOException {
+        write("'/>\n</svg>\n");
+    }
+
+    private void execute(final String s) throws IOException {
+        write("M%g,%g\n", currentX, currentY);
+        for (int i = 0, n = s.length(); i < n; ++i) {
+            switch (s.charAt(i)) {
+                case 'F':
+                    line(lineLength);
+                    break;
+                case '+':
+                    turn(ANGLE);
+                    break;
+                case '-':
+                    turn(-ANGLE);
+                    break;
+            }
+        }
+    }
+
+    private void line(final double length) throws IOException {
+        final double theta = (Math.PI * currentAngle) / 180.0;
+        currentX += length * Math.cos(theta);
+        currentY += length * Math.sin(theta);
+        write("L%g,%g\n", currentX, currentY);
+    }
+
+    private void turn(final int angle) {
+        currentAngle = (currentAngle + angle) % 360;
+    }
+
+    private void write(final String format, final Object... args) throws IOException {
+        writer.write(String.format(format, args));
+    }
+
+    private static String rewrite(final int order) {
+        String s = "L";
+        for (int i = 0; i < order; ++i) {
+            final StringBuilder sb = new StringBuilder();
+            for (int j = 0, n = s.length(); j < n; ++j) {
+                final char ch = s.charAt(j);
+                if (ch == 'L')
+                    sb.append("LFRFL-F-RFLFR+F+LFRFL");
+                else if (ch == 'R')
+                    sb.append("RFLFR+F+LFRFL-F-RFLFR");
+                else
+                    sb.append(ch);
+            }
+            s = sb.toString();
+        }
+        return s;
+    }
+
+    private final Writer writer;
+    private double lineLength;
+    private double currentX;
+    private double currentY;
+    private int currentAngle;
+    private static final int ANGLE = 90;
+}