There a two classes Queens.java and TestQueens.java in the Source Package EightQueens

If possible would you please complete the implementation of the following Queens class complete the body for all methods marked as To be implemented in Programming Problem 1. Do not change any of the global variable declarations, constructor or placeQueens methods.

The programs output should look similar to:

|1|0|0|0|0|0|0|0|

|0|0|0|0|0|0|1|0|

|0|0|0|0|1|0|0|0|

|0|0|0|0|0|0|0|1|

|0|1|0|0|0|0|0|0|

|0|0|0|1|0|0|0|0|

|0|0|0|0|0|1|0|0|

|0|0|1|0|0|0|0|0|

package EightQueens;

public class Queens {

// squares per row or column

public static final int BOARD_SIZE = 8;

// used to indicate an empty square

public static final int EMPTY = 0;

// used to indicate square contains a queen

public static final int QUEEN = 1;

private int board[][]; // chess board

public Queens() {

// -------------------------------------------------

// Constructor: Creates an empty square board.

// -------------------------------------------------

board = new int[BOARD_SIZE][BOARD_SIZE];

} // end constructor

public void clearBoard() {

// -------------------------------------------------

// Clears the board.

// Precondition: None.

// Postcondition: Sets all squares to EMPTY.

// ------------------------------------------------- // To be implemented in Programming Problem 1 } // end clearBoard public void displayBoard() {

// -------------------------------------------------

// Displays the board.

// Precondition: None.

// Postcondition: Board is written to standard

// output; zero is an EMPTY square, one is a square

// containing a queen (QUEEN).

// ------------------------------------------------- // To be implemented in Programing Project 1 } // end displayBoard public boolean placeQueens(int column) {

// -------------------------------------------------

// Places queens in columns of the board beginning

// at the column specified.

// Precondition: Queens are placed correctly in

// columns 1 through column-1.

// Postcondition: If a solution is found, each

// column of the board contains one queen and method

// returns true; otherwise, returns false (no

// solution exists for a queen anywhere in column

// specified).

// -------------------------------------------------

if (column > BOARD_SIZE) {

return true; // base case

}

else {

boolean queenPlaced = false;

int row = 0; // number of square in column

while ( !queenPlaced && (row < BOARD_SIZE) ) {

// if square can be attacked

if (isUnderAttack(row, column)) {

++row; // consider next square in column

} // end if

else { // place queen and consider next column

setQueen(row, column);

queenPlaced = placeQueens(column+1);

// if no queen is possible in next column,

if (!queenPlaced) {

// backtrack: remove queen placed earlier

// and try next square in column

removeQueen(row, column);

++row;

} // end if

} // end if

} // end while return queenPlaced;

} // end if

} // end placeQueens

private void setQueen(int row, int column) {

// --------------------------------------------------

// Sets a queen at square indicated by row and

// column.

// Precondition: None.

// Postcondition: Sets the square on the board in a

// given row and column to QUEEN.

// -------------------------------------------------- // To be implemented in Programing Problem 1 // end setQueen } private void removeQueen(int row, int column) {

// --------------------------------------------------

// Removes a queen at square indicated by row and

// column.

// Precondition: None.

// Postcondition: Sets the square on the board in a

// given row and column to EMPTY.

// -------------------------------------------------- // To be implemented in Programming Problem 1

} // end removeQueen

private boolean isUnderAttack(int row, int column) {

// --------------------------------------------------

// Determines whether the square on the board at a

// given row and column is under attack by any queens

// in the columns 1 through column-1.

// Precondition: Each column between 1 and column-1

// has a queen placed in a square at a specific row.

// None of these queens can be attacked by any other

// queen.

// Postcondition: If the designated square is under

// attack, returns true; otherwise, returns false.

// -------------------------------------------------- // To be implemented in Programing Problem 1 } // end isUnderAttack private int index(int number) {

// --------------------------------------------------

// Returns the array index that corresponds to

// a row or column number.

// Precondition: 1 <= number <= BOARD_SIZE.

// Postcondition: Returns adjusted index value.

// --------------------------------------------------

// To be implemented in Programming Problem 1

} // end index

} // end Queens

And an Implementation of the "Using placeQueens" pseudocode

package EightQueens;

public class TestQueens { placeQueens(1) //begin with the first //column if (a solution exists) { Display solution } else { Display message // no solution found } // end if