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| import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import java.util.HashSet;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class PathFinder {
ArrayList<Node> open = new ArrayList();
HashSet<Node> closed = new HashSet();
int width, height;
int[][] map;
int targetX, targetY;
int startX, startY;
private JFrame frame;
public static void main (String[] args) {
PathFinder p = new PathFinder();
p.width = 18;
p.height = 16;
p.map = new int[p.width][p.height];
p.map[4][1] = -1;
p.map[4][2] = -1;
p.map[4][3] = -1;
p.startX = 2;
p.startY = 2;
p.targetX = 16;
p.targetY = 12;
p.run();
}
private void run () {
frame = new JFrame();
frame.getContentPane().setLayout(new GridLayout(height, width, 5, 5));
frame.addMouseMotionListener(new MouseMotionListener() {
public void mouseDragged (MouseEvent e) {
}
public void mouseMoved (MouseEvent e) {
startX = (int)(e.getX() / 800f * width);
startY = (int)(e.getY() / 600f * height);
update();
}
});
frame.setSize(800, 600);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
update();
}
void update () {
frame.getContentPane().removeAll();
ArrayList<int[]> path = go();
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
JPanel panel = new JPanel();
panel.setOpaque(true);
panel.setBackground(map[x][y] == 0 ? Color.black : Color.red);
if (path != null) {
for (int[] coord : path)
if (x == coord[0] && y == coord[1]) panel.setBackground(Color.green);
}
if (x == startX && y == startY) panel.setBackground(Color.blue);
if (x == targetX && y == targetY) panel.setBackground(Color.blue);
frame.getContentPane().add(panel);
}
}
frame.validate();
}
public ArrayList<int[]> go () {
long start = System.nanoTime();
open.clear();
closed.clear();
Node root = new Node(null, startX, startY, 0);
open.add(root);
while (!open.isEmpty()) {
int lowestIndex = -1;
int lowestCost = Integer.MAX_VALUE;
for (int i = 0, n = open.size(); i < n; i++) {
Node node = open.get(i);
int cost = node.g + node.h;
if (cost < lowestCost) {
lowestCost = cost;
lowestIndex = i;
}
}
Node check = open.remove(lowestIndex);
if (check.x == targetX && check.y == targetY) {
ArrayList<int[]> path = new ArrayList();
while (check != root) {
path.add(0, new int[] {check.x, check.y});
check = check.parent;
}
long end = System.nanoTime();
System.out.println((end - start) / 1000000f);
return path;
}
closed.add(check);
addNode(check, check.x, check.y + 1, 10);
addNode(check, check.x, check.y - 1, 10);
addNode(check, check.x + 1, check.y, 10);
addNode(check, check.x - 1, check.y, 10);
addNode(check, check.x + 1, check.y + 1, 14);
addNode(check, check.x - 1, check.y - 1, 14);
addNode(check, check.x + 1, check.y - 1, 14);
addNode(check, check.x - 1, check.y + 1, 14);
}
return null;
}
private void addNode (Node parent, int x, int y, int cost) {
if (x < 0 || y < 0) return;
if (x >= width || y >= height) return;
if (map[x][y] != 0) return;
Node node = new Node(parent, x, y, cost);
if (closed.contains(node)) return;
int existingIndex = open.indexOf(node);
if (existingIndex == -1) {
open.add(node);
} else {
Node existing = open.get(existingIndex);
if (node.g < existing.g) {
existing.parent = parent;
existing.g = node.g;
}
}
}
private class Node {
public Node parent;
public int x, y;
public int g, h;
public Node (Node parent, int x, int y, int cost) {
this.parent = parent;
this.x = x;
this.y = y;
g = parent == null ? 0 : parent.g + cost;
h = Math.abs(x - targetX) + Math.abs(y - targetY);
h *= 10;
}
public int hashCode () {
int result = 1;
result = 31 * result + x;
result = 31 * result + y;
return result;
}
public boolean equals (Object object) {
Node node = (Node)object;
return node.x == x && node.y == y;
}
}
} |
