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Maze.java
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Maze.java
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import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Maze {
// private static class Positions {
// private int row;
// private int col;
//
// public Positions(int row, int col) {
// this.row = row;
// this.col = col;
// }
//
// public int up() {
// return new int[] {row - 1, col};
// }
//
// public int down() {
// return new int[] {row + 1, col};
// }
//
// // finish??
// }
private static int[][] positions = new int[][] {
// up
{ -1, 0 },
// down
{ 1, 0 },
// right
{ 0, 1 },
// left
{ 0, -1 } };
private String[][] maze;
private boolean animate;// false by default
private int startRow, startCol;
/**
* Constructor loads a maze text file, and sets animate to false by default.
* <ol>
* <li>The file contains a rectangular ascii maze, made with the following 4
* characters: '#' - Walls - locations that cannot be moved onto ' ' - Empty
* Space - locations that can be moved onto 'E' - the location of the goal
* (exactly 1 per file)
*
* 'S' - the location of the start(exactly 1 per file)</li>
* <li>The maze has a border of '#' around the edges. So you don't have to check
* for out of bounds!</li>
* </ol>
*
* @throws IOException
* @throws FileNotFoundException When the file is not found
* @throws IllegalStateException When the file is invalid (not exactly 1 E and 1
* S)
*
*/
public Maze(String filename) throws FileNotFoundException, IOException {
// COMPLETE CONSTRUCTOR
String filepath = filename;
// For running from eclipse
// String filepath = System.getProperty("user.dir").concat("\\src\\recursion\\" + filename);
// For running from bash in /bin
// filepath = System.getProperty("user.dir").concat("\\..\\src\\recursion\\" +
// filename);
// debug
// System.out.println(filepath);
StringBuilder lines = new StringBuilder();
final String lnBk = System.lineSeparator();
try (BufferedReader file = new BufferedReader(new FileReader(filepath));) {
String line = file.readLine();
while (line != null) {
// debug
// System.out.println(line);
lines.append(line);
lines.append(lnBk);
line = file.readLine();
}
}
String lineStr = lines.toString();
Matcher m = Pattern.compile("[E|S]").matcher(lineStr);
int ECount = 0, SCount = 0;
int posS = 0;
while (m.find()) {
String c = m.group();
if (c.equals("E"))
ECount++;
else if (c.equals("S")) {
SCount++;
posS = m.start();
}
}
if (ECount != 1 || SCount != 1) {
System.err.println(lineStr);
throw new IllegalStateException("File should contain exactly 1 E and 1 S");
}
String[] rows = lineStr.split(lnBk);
String[][] charArray = new String[rows.length][rows[0].length()];
for (int i = 0; i < rows.length; i++) {
charArray[i] = rows[i].split("");
}
// this.startRow = posS / charArray[0].length + lnBk.length() - 2;
// this.startCol %= charArray[0].length + lnBk.length();
for (int i = 0; i < rows.length; i++) {
if (rows[i].contains("S")) {
this.startRow = i;
this.startCol = rows[i].indexOf("S");
}
}
// debug
// System.out.format("Row: %d Col: %d%n", startRow, startCol);
this.maze = charArray;
this.setAnimate(false);
}
private void wait(int millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
}
}
public void setAnimate(boolean b) {
animate = b;
}
public void clearTerminal() {
// erase terminal, go to top left of screen.
System.out.println("\033[2J\033[1;1H");
}
/**
* Wrapper Solve Function returns the helper function
*
* Note the helper function has the same name, but different parameters. Since
* the constructor exits when the file is not found or is missing an E or S, we
* can assume it exists.
*
*/
public int solve() {
// find the location of the S.
// erase the S
// and start solving at the location of the s.
// return solve(???,???);
this.maze[startRow][startCol] = " ";
return solve(startRow, startCol, 0);
}
/**
* Recursive Solve function:
*
* A solved maze has a path marked with '@' from S to E.
*
* Returns the number of @ symbols from S to E when the maze is solved, Returns
* -1 when the maze has no solution.
*
*
* Postcondition:
*
* The S is replaced with '@' but the 'E' is not.
*
* All visited spots that were not part of the solution are changed to '.'
*
* All visited spots that are part of the solution are changed to '@'
*/
private int solve(int row, int col, int level) { // you can add more parameters since this is private
// automatic animation! You are welcome.
if (animate) {
clearTerminal();
System.out.println(this);
wait(20);
}
// debug
// System.out.println(level);
// COMPLETE SOLVE
if (maze[row][col].equals(" ")) {
// try all directions
maze[row][col] = "@";
//
// int up = solve(row - 1, col, level + 1);
// if (up != -1)
// return up;
// int down = solve(row + 1, col, level + 1);
// if (down != -1)
// return down;
// int right = solve(row, col + 1, level + 1);
// if (right != -1)
// return right;
for (int[] pos : positions) {
int result = solve(row + pos[0], col + pos[1], level + 1);
if (result != -1)
return result;
}
maze[row][col] = ".";
return -1;
} else if (maze[row][col].equals("E")) {
return level;
} else {
return -1;
}
}
@Override
public String toString() {
StringBuilder str = new StringBuilder();
for (String[] row : this.maze) {
for (String c : row) {
str.append(c);
}
str.append(String.format("%n"));
}
return str.toString();
}
}