import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class GreedSnake implements KeyListener{
JFrame mainFrame;
Canvas paintCanvas;
JLabel labelScore;
SnakeModel snakeModel = null;

public static final int canvasWidth = 400;
public static final int canvasHeight = 300;

public static final int nodeWidth = 8;
public static final int nodeHeight = 8;

public GreedSnake() {
mainFrame = new JFrame("GreedSnake");

Container cp = mainFrame.getContentPane();

labelScore = new JLabel("Score:");
cp.add(labelScore, BorderLayout.NORTH);

paintCanvas = new Canvas();
paintCanvas.setSize(canvasWidth+1,canvasHeight+1);
paintCanvas.addKeyListener(this);
cp.add(paintCanvas, BorderLayout.CENTER);

JPanel panelButtom = new JPanel();
panelButtom.setLayout(new BorderLayout());
JLabel labelHelp;
labelHelp = new JLabel("PageUp, PageDown for speed;", JLabel.CENTER);
panelButtom.add(labelHelp, BorderLayout.NORTH);
labelHelp = new JLabel("ENTER or R or S for start;", JLabel.CENTER);
panelButtom.add(labelHelp, BorderLayout.CENTER);
labelHelp = new JLabel("SPACE or P for pause",JLabel.CENTER);
panelButtom.add(labelHelp, BorderLayout.SOUTH);
cp.add(panelButtom,BorderLayout.SOUTH);

mainFrame.addKeyListener(this);
mainFrame.pack();
mainFrame.setResizable(false);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setVisible(true);
begin();
}

public void keyPressed(KeyEvent e){
int keyCode = e.getKeyCode();
if (snakeModel.running)
switch(keyCode){
case KeyEvent.VK_UP:
snakeModel.changeDirection(SnakeModel.UP);
break;
case KeyEvent.VK_DOWN:
snakeModel.changeDirection(SnakeModel.DOWN);
break;
case KeyEvent.VK_LEFT:
snakeModel.changeDirection(SnakeModel.LEFT);
break;
case KeyEvent.VK_RIGHT:
snakeModel.changeDirection(SnakeModel.RIGHT);
break;
case KeyEvent.VK_ADD:
case KeyEvent.VK_PAGE_UP:
snakeModel.speedUp();
break;
case KeyEvent.VK_SUBTRACT:
case KeyEvent.VK_PAGE_DOWN:
snakeModel.speedDown();
break;
case KeyEvent.VK_SPACE:
case KeyEvent.VK_P:
snakeModel.changePauseState();
break;
default:
}

if (keyCode == KeyEvent.VK_R ||
keyCode == KeyEvent.VK_S ||
keyCode == KeyEvent.VK_ENTER){
snakeModel.running = false;
begin();
}
}

public void keyReleased(KeyEvent e){
}

public void keyTyped(KeyEvent e){
}
void repaint(){
Graphics g = paintCanvas.getGraphics();

//draw background
g.setColor(Color.WHITE);
g.fillRect(0,0,canvasWidth,canvasHeight);

// draw the snake
g.setColor(Color.GREEN);
LinkedList na = snakeModel.nodeArray;
Iterator it = na.iterator();
while(it.hasNext()){
Node n = (Node)it.next();
drawNode(g,n);
}

// draw the food
g.setColor(Color.RED);
Node n = snakeModel.food;
drawNode(g,n);

updateScore();
}

private void drawNode(Graphics g, Node n){
g.fillRect(n.x*nodeWidth,
n.y*nodeHeight,
nodeWidth-1,
nodeHeight-1);
}

public void updateScore(){
String s = "Score: " + snakeModel.score;
labelScore.setText(s);
}

void begin(){
if (snakeModel == null || !snakeModel.running){
snakeModel = new SnakeModel(this,
canvasWidth/nodeWidth,
canvasHeight/nodeHeight);
(new Thread(snakeModel)).start();
}
}

public static void main(String[] args){
GreedSnake gs = new GreedSnake();
}
}
import java.util.*;
import javax.swing.*;

class SnakeModel implements Runnable{
GreedSnake gs;
boolean[][] matrix;
LinkedList nodeArray = new LinkedList();
Node food;
int maxX;
int maxY;
int direction = 2;
boolean running = false;

int timeInterval = 200;
double speedChangeRate = 0.75;
boolean paused = false;

int score = 0;
int countMove = 0;

// UP and DOWN should be even
// RIGHT and LEFT should be odd
public static final int UP = 2;
public static final int DOWN = 4;
public static final int LEFT = 1;
public static final int RIGHT = 3;

public SnakeModel(GreedSnake gs, int maxX, int maxY){
this.gs = gs;
this.maxX = maxX;
this.maxY = maxY;

// initial matirx
matrix = new boolean[maxX][];
for(int i=0; i<maxX; ++i){
matrix[i] = new boolean[maxY];
Arrays.fill(matrix[i],false);
}

// initial the snake
int initArrayLength = maxX > 20 ? 10 : maxX/2;
for(int i = 0; i < initArrayLength; ++i){
int x = maxX/2+i;
int y = maxY/2;
nodeArray.addLast(new Node(x, y));
matrix[x][y] = true;
}

food = createFood();
matrix[food.x][food.y] = true;
}

public void changeDirection(int newDirection){
if (direction % 2 != newDirection % 2){
direction = newDirection;
}
}

public boolean moveOn(){
Node n = (Node)nodeArray.getFirst();
int x = n.x;
int y = n.y;

switch(direction){
case UP:
y--;
break;
case DOWN:
y++;
break;
case LEFT:
x--;
break;
case RIGHT:
x++;
break;
}

if ((0 <= x && x < maxX) && (0 <= y && y < maxY)){
if (matrix[x][y]){
if(x == food.x && y == food.y){
nodeArray.addFirst(food);

int scoreGet = (10000 - 200 * countMove) / timeInterval;
score += scoreGet > 0? scoreGet : 10;
countMove = 0;
food = createFood();
matrix[food.x][food.y] = true;
return true;
}
else
return false;
}
else{
nodeArray.addFirst(new Node(x,y));
matrix[x][y] = true;
n = (Node)nodeArray.removeLast();
matrix[n.x][n.y] = false;
countMove++;
return true;
}
}
return false;
}
public void run(){
running = true;
while (running){
try{
Thread.sleep(timeInterval);
}
catch(Exception e){
break;
}

if(!paused){
if (moveOn()){
gs.repaint();
}
else{
JOptionPane.showMessageDialog(
null,
"you failed",
"Game Over",
JOptionPane.INformATION_MESSAGE);
break;
}
}
}
running = false;
}

private Node createFood(){
int x = 0;
int y = 0;
do{
Random r = new Random();
x = r.nextInt(maxX);
y = r.nextInt(maxY);
}while(matrix[x][y]);

return new Node(x,y);
}

public void speedUp(){
timeInterval *= speedChangeRate;
}

public void speedDown(){
timeInterval /= speedChangeRate;
}

public void changePauseState(){
paused = !paused;
}

public String toString(){
String result = "";
for(int i=0; i<nodeArray.size(); ++i){
Node n = (Node)nodeArray.get(i);
result += "[" + n.x + "," + n.y + "]";
}
return result;
}
}

class Node{
int x;
int y;
Node(int x, int y){
this.x = x;
this.y = y;
}
}