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Maze Design
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Maze Design
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Source:
http://www.careercup.com/question?id=15579675
Design a maze. Give the algorithm and code to find the correct path and get out of the maze.
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Stack;
public class Maze {
public static void main(String[] args) {
//Use 2D array
int[][] maze = new int[6][6];
maze[0] = new int[] { 1, 1, 0, 0, 0, 0 };
maze[1] = new int[] { 0, 1, 0, 0, 0, 0 };
maze[2] = new int[] { 0, 1, 0, 1, 1, 1 };
maze[3] = new int[] { 1, 1, 1, 1, 0, 1 };
maze[4] = new int[] { 0, 1, 0, 0, 0, 1 };
maze[5] = new int[] { 0, 1, 0, 0, 0, 1 };
//This is the start of exit point of maze
Point start = new Point(0,0);
Point exit = new Point(5,5);
//DFS approach
Stack<Point> s = new Stack<Point>();
s.push(start);
Map<Point,Status> visited = new HashMap<Point,Status>();
visited.put(start, Status.VISITING);
while(!s.isEmpty()){
Point currentP = s.peek();
boolean isAllVisited = true;
for (Point p : getAdjacent(currentP.x, currentP.y)){
//It should be y and x, see above array
if (visited.get(p)==null && maze[p.y][p.x]==1){
visited.put(p, Status.VISITING);
isAllVisited = false ;
s.push(p);
if ( p.equals(exit)){
printPath(s);
}
break;
}
}
if (isAllVisited){
visited.put(currentP, Status.VISITED);
s.pop();
}
}
}
private static void printPath(Stack<Point> s){
while (!s.isEmpty()){
System.out.print("->");
Point p = s.remove(0);
System.out.format("[%d,%d]",p.x,p.y);
}
}
private static List<Point> getAdjacent(int x, int y){
List<Point> result = new ArrayList<Point>();
//above point;
if (y-1>=0) {
result.add(new Point(x, y-1));
};
//right point;
if (x+1<=5) {
result.add(new Point(x+1, y));
};
//below point;
if (y+1<=5) {
result.add(new Point(x, y+1));
};
//left point;
if (x-1>=0) {
result.add(new Point(x-1, y));
};
return result;
}
private static class Point {
int x, y;
public Point(int x,int y) {
this.x = x;
this.y = y;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + x;
result = prime * result + y;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Point other = (Point) obj;
if (x != other.x)
return false;
if (y != other.y)
return false;
return true;
}
}
private static enum Status {
UNVISITED, VISITING, VISITED
};
}