Completed clue4

src/clue4/Main.java

@@ -0,0 +1,78 @@
+package clue4;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+
+public class Main {
+
+	public static void main(String[] args) {
+		try {
+			FileInputStream stream = new FileInputStream("clue4.png");
+			BufferedImage image = ImageIO.read(stream);
+			stream.close();
+			int width  = image.getWidth();
+			int height = image.getHeight();
+			int[] raw  = image.getRGB(0, 0, width, height, null, 0, width);
+			int[] output = new int[width * height];
+
+			rotateSections(315, 0xFF0000FF, width, height, raw, output);
+			rotateSections(126, 0xFF00FF00, width, height, output, raw);
+			rotateSections(63,  0xFFFF0000, width, height, raw, output);
+			rotateSections(45,  0xFF00FFFF, width, height, output, raw);
+			rotateSections(21,  0xFFFFFF00, width, height, raw, output);
+			rotateSections(7,   0xFFFF00FF, width, height, output, raw);
+
+			image.setRGB(0, 0, width, height, raw , 0, width);
+			ImageIO.write(image, "png", new File("clue4_output.png"));
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+
+	static void rotateSections(int dim, int targetColor, int width, int height, int[] read, int[] write) {
+		for (int i = 0; i < width; i += dim) {
+			for (int j = 0; j < height; j += dim) {
+				Rotate rotate = Main::rotate0;
+				if (read[(i + dim - 1) + j * width] == targetColor)
+					rotate = Main::rotate90;
+				else if (read[i + (j + dim - 1) * width] == targetColor)
+					rotate = Main::rotate270;
+				else if (read[(i + dim - 1) + (j + dim - 1) * width] == targetColor)
+					rotate = Main::rotate180;
+				for (int k = 0; k < dim * dim; ++k) {
+					int rotated = rotate.rotate(dim, k);
+					write[(i + k % dim) + (j + k / dim) * width] = read[(i + rotated % dim) + (j + rotated / dim) * width];
+				}
+			}
+		}
+	}
+
+	interface Rotate {
+		int rotate(int width, int index);
+	}
+
+	private static int rotate0(int dim, int index) {
+		return index;
+	}
+
+	private static int rotate90(int dim, int index) {
+		int x = -index / dim;
+		int y =  index % dim;
+		return (x + dim - 1) + y * dim;
+	}
+
+	private static int rotate180(int dim, int index) {
+		int x = -index % dim;
+		int y = -index / dim;
+		return (x + dim - 1) + (y + dim - 1) * dim;
+	}
+
+	private static int rotate270(int dim, int index) {
+		int x =  index / dim;
+		int y = -index % dim;
+		return x + (y + dim - 1) * dim;
+	}
+}