Java Knights Tourcode

Question

Ich habe einige Probleme mit dem folgenden Code. Zuerst kann ich mir nicht vorstellen, wie ich verhindern kann, dass das Stück ins Aus geht. Zweitens, wenn der Code funktioniert, fügt er die Schritte nicht richtig hinzu.

package runknightstour; 

public class RunKnightsTour 
{ 
    public static void main(String[] args) 
    {  
     KnightMoves tour = new KnightMoves();  
     tour.runTour(); 
    } 
} 

package runknightstour; 

public class ChessBoard 
{ 
    public final int ROWS = 8; 
    public final int COLS = 8; 
    public final int FRAMESIZE = 12; 
    private int[][] board = new int[FRAMESIZE][FRAMESIZE]; 

    public ChessBoard() 
    { 
     for (int y = 0; y < board.length; y++) { 
      for (int x = 0; x < board[y].length; x++) { 
       board[y][x] = -1; 
      } 
      for (int r = 2; r < ROWS + 2; r++) { 
       for (int c = 2; c < COLS + 2; c++) { 
        board[r][c] = 0; 
       } 
      } 
     } 
    } 
    public String toString() 
    { 
     String output = ""; 
     for (int r = 0; r < FRAMESIZE; r++) { 
      for (int c = 0; c < FRAMESIZE; c++) { 
       output += board[r][c]; 
       output += "\t"; 
      } 
      output += "\n\n"; 
     } 
     return output; 
    } 
    /** 
    * 
    * @param row 
    * @param col 
    * @param inStep in the range of 1 - 64 
    */  
    public void setSquare(int row, int col, int inStep) 
    { 
     // adjust input to match 2 - 9 
     row += 1; 
     col +=1; 
     if (row > 1 && row < 10 && col > 1 && col < 10) 
     { 
      board[row][col] = inStep; 
     } 
    } 
    public int getSquare (int row, int col) 
    { 
     return board[row][col]; 
    } 
} 
package runknightstour; 
import java.util.Random; 
import java.util.Scanner; 

public class KnightMoves 
{ 
    public final int COMPLETE_TOUR = 64; 
    private ChessBoard kBoard = new ChessBoard(); 
    private int[][] moves = new int[8][2]; 
    private int stepNumber; 
    private int currentRow; 
    private int currentCol; 
    private int startRow; 
    private int startCol; 


    public KnightMoves() 
    { 
     moves[0][0] = -2; // move 0 row offset 
     moves[0][1] = 1; // move 0 col offset 

     moves[1][0] = -1; // move 1 row offset 
     moves[1][1] = 2; // move 1 col offset 

     moves[2][0] = 1; // move 2 row offset 
     moves[2][1] = 2; // move 2 col offset 

     moves[3][0] = 2; // move 3 row offset 
     moves[3][1] = 1; // move 3 col offset 

     moves[4][0] = 2; // move 4 row offset 
     moves[4][1] = -1; // move 4 col offset 

     moves[5][0] = 1; // move 5 row offset 
     moves[5][1] = -2; // move 5 col offset 

     moves[6][0] = -1; // move 6 row offset 
     moves[6][1] = -2; // move 6 col offset 

     moves[7][0] = -2; // move 7 row offset 
     moves[7][1] = -1; // move 7 col offset 

     stepNumber = 0; 
     startRow = startCol = 1; 
     currentRow = currentCol = 1; 
    } 
    /** 
    * Description: Get the starting board Position (row, col) for the 
    *    KNIGHT from program user 
    */ 
    public void getStartPosition() 
    { 
     Scanner input = new Scanner(System.in); 
     System.out.print("\n enter a starting location for the knight's row "); 
     startRow = input.nextInt(); 
     System.out.print("\n enter a starting location for the knight's col "); 
     startCol = input.nextInt(); 

     kBoard.setSquare(startRow, startCol, 1); 

     System.out.println(kBoard); 
    } 
    /** 
    * Mutator: runTour() 
    */ 
    public void runTour() 
    { 
     getStartPosition(); 

     // if stepNumber is equal to COMPLETE_TOUR 
     // report that the knight made a complete tour 
     do { 
      takeStep(); 
     } 
     while (stepNumber < 64 && takeStep()== true); 

     System.out.println(kBoard); 
     System.out.println(toString());  
    } 

    private boolean takeStep() 
    { 
     boolean stepTaken = true; 
     int random1; 
     Random rand = new Random(); 
     random1 = rand.nextInt(8); 
     int tryStepRow =0; 
     int tryStepCol=0; 
     int attempts =0; 
     do { 
      tryStepRow = currentRow + moves[random1][0]; 
      tryStepCol = currentCol + moves[random1][1]; 
      if(kBoard.getSquare(tryStepRow,tryStepCol)==0) 
      { 
       kBoard.setSquare(tryStepRow,tryStepCol, stepNumber++); 
       currentRow= tryStepRow; 
       currentCol = tryStepCol; 
      } 
      else 
      { 
       attempts++; 
      }    
     } while (stepTaken == false && attempts < 200); 
     return stepTaken; 
    } 
    public String toString() 
    { 
     String whatHappened = ""; 
     whatHappened += "Starting location: [" + startRow + ", " 
     + startCol + "]\n"; 
     whatHappened += " Tour ended after " + stepNumber + " steps\n"; 
     whatHappened += "The knight got stuck in location [" 
     + (currentRow) + ", " + (currentCol) + "]\n"; 
     return whatHappened; 

    } 
} 

Beispiel Nachricht ich bekomme.

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1 
at runknightstour.ChessBoard.getSquare(ChessBoard.java:68) 
at runknightstour.KnightMoves.takeStep(KnightMoves.java:101) 
at runknightstour.KnightMoves.runTour(KnightMoves.java:80) 
at runknightstour.RunKnightsTour.main(RunKnightsTour.java:22) 
I:\CSC122\RunKnightsTour\nbproject\build-impl.xml:1039: The following error   occurred while executing this line: 
I:\CSC122\RunKnightsTour\nbproject\build-impl.xml:804: Java returned: 1 
BUILD FAILED (total time: 2 seconds) 

Answer 1

Wenn Sie genau die Funktion sehen setSquare() Sie werden feststellen, dass es in eine Endlosschleife wird, da es keine Erhöhung Bedingungen auf row oder col gegeben ist. Wenn Ihre board Größe nicht groß genug ist, können Sie am Ende ArraysOutOfBounds Ausnahme bekommen.

public void setSquare(int row, int col, int inStep) 
{ 
    // adjust input to match 2 - 9 
    row += 1; 
    col += 1; 
    if (row > 1 && row < 10 && col > 1 && col < 10) 
    { 
     /* Where are you incrementing row/col? */ 
     board[row][col] = inStep; 
    } 
}