Completed clue2

src/clue0/Main.java

@@ -12,6 +12,7 @@ public class Main {
 		try {
 			FileInputStream stream = new FileInputStream("clue0.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);
@@ -47,14 +48,12 @@ public class Main {
 
 			image.setRGB(0, 0, width, height, output, 0, width);
 			ImageIO.write(image, "png", new File("clue0_output.png"));
-
-			stream.close();
 		} catch (IOException e) {
 			e.printStackTrace();
 		}
 	}
 
-	public static int rotate(int index, int shift, int mod) {
+	private static int rotate(int index, int shift, int mod) {
 		return (((index % mod + shift % mod) % mod) + mod) % mod;
 	}
 }

src/clue1/Main.java

@@ -12,6 +12,7 @@ public class Main {
 		try {
 			FileInputStream stream = new FileInputStream("clue1.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);

src/clue2/Main.java

@@ -0,0 +1,54 @@
+package clue2;
+
+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("clue2.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];
+
+			int x = 0;
+			int y = 0;
+			int dir = 1;
+			for (int i = 0; i < width * height; ++i) {
+				output[i] = raw[x + y * width];
+				if (dir == -1 && y == height - 1) {
+					++x;
+					dir = -dir;
+				}
+				else if (dir == -1 && x == 0) {
+					 ++y;
+					dir = -dir;
+				}
+				else if (dir == 1 && x == width - 1) {
+					++y;
+					dir = -dir;
+				}
+				else if (dir == 1 && y == 0) {
+					++x;
+					dir = -dir;
+				}
+				else {
+					x += dir;
+					y -= dir;
+				}
+			}
+
+			image.setRGB(0, 0, width, height, output, 0, width);
+			ImageIO.write(image, "png", new File("clue2_output.png"));
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+}