N queen problem for c++. It must include the following functions: bool** ReadChe
ID: 3746956 • Letter: N
Question
N queen problem for c++.
It must include the following functions:
bool** ReadChessboard(char* filepath, int& num_rows, int& num_cols);
void PrintChessboard( bool** board, int num_rows, int num_cols);
int main(int argc, char* argc[]);
Here is some of the code provided. I need the code for where it say "Modify and enter your code here."
#include <iostream>
#include <fstream>
using namespace std;
bool** ReadChessboard(char* filepath, int& num_rows, int& num_cols)
{
fstream infile;
infile.open(filepath);
infile >> num_rows;
infile >> num_cols;
/////////////////////////////////////////////////////////////////
// Modify and enter your code here, to create board with adding
// queens into the board.
return NULL;
/////////////////////////////////////////////////////////////////
}
void PrintChessboard(bool** board, int num_rows, int num_cols)
{
cout << "Print chess board:" << endl << endl;
/////////////////////////////////////////////////////////////////
// Enter your code here, to print chess board with queens.
// * " Q" to print a queen, and
// * " ." to print an empty cell.
/////////////////////////////////////////////////////////////////
}
/////////////////////////////////////////////////////////////////////
// Add your own functions if you need
/////////////////////////////////////////////////////////////////////
int main(int argc, char* argv[])
{
if(argc <= 1)
{
cout << "Need the input file containing chess board size and queen locations." << endl;
return 0;
}
int num_rows;
int num_cols;
bool** board = ReadChessboard(argv[1], num_rows, num_cols);
PrintChessboard(board, num_rows, num_cols);
bool is_nqueens = false;
bool there_are_attacks = false;
/////////////////////////////////////////////////////////////////
// Enter your code here.
// If you want create your own functions
/////////////////////////////////////////////////////////////////
if(is_nqueens)
cout << "Solution to the N Queen Problem? Yes" << endl << endl;
else
cout << "Solution to the N Queen Problem? No" << endl << endl;
if(there_are_attacks)
{
cout << "There is at least one queen attacking other queen(s)." << endl;
/////////////////////////////////////////////////////////////////
// Enter your code to print list of queens attacking other queens
/////////////////////////////////////////////////////////////////
}
else
{
cout << "There is no queen attacking other queen(s)." << endl;
}
/////////////////////////////////////////////////////////////////
// Enter your code to delete dynamically allocated memories
/////////////////////////////////////////////////////////////////
}
Explanation / Answer
/* C/C++ program to solve N Queen Problem using
backtracking */
#define N 4
#include<stdio.h>
#include<stdbool.h>
/* A utility function to print solution */
void printSolution(int board[N][N])
{
for (int i = 0; i < N; i++)
{
for (int j = 0; j < N; j++)
printf(" %d ", board[i][j]);
printf(" ");
}
}
/* A utility function to check if a queen can
be placed on board[row][col]. Note that this
function is called when "col" queens are
already placed in columns from 0 to col -1.
So we need to check only left side for
attacking queens */
bool isSafe(int board[N][N], int row, int col)
{
int i, j;
/* Check this row on left side */
for (i = 0; i < col; i++)
if (board[row][i])
return false;
/* Check upper diagonal on left side */
for (i=row, j=col; i>=0 && j>=0; i--, j--)
if (board[i][j])
return false;
/* Check lower diagonal on left side */
for (i=row, j=col; j>=0 && i<N; i++, j--)
if (board[i][j])
return false;
return true;
}
/* A recursive utility function to solve N
Queen problem */
bool solveNQUtil(int board[N][N], int col)
{
/* base case: If all queens are placed
then return true */
if (col >= N)
return true;
/* Consider this column and try placing
this queen in all rows one by one */
for (int i = 0; i < N; i++)
{
/* Check if the queen can be placed on
board[i][col] */
if ( isSafe(board, i, col) )
{
/* Place this queen in board[i][col] */
board[i][col] = 1;
/* recur to place rest of the queens */
if ( solveNQUtil(board, col + 1) )
return true;
/* If placing queen in board[i][col]
doesn't lead to a solution, then
remove queen from board[i][col] */
board[i][col] = 0; // BACKTRACK
}
}
/* If the queen cannot be placed in any row in
this colum col then return false */
return false;
}
/* This function solves the N Queen problem using
Backtracking. It mainly uses solveNQUtil() to
solve the problem. It returns false if queens
cannot be placed, otherwise, return true and
prints placement of queens in the form of 1s.
Please note that there may be more than one
solutions, this function prints one of the
feasible solutions.*/
bool solveNQ()
{
int board[N][N] = { {0, 0, 0, 0},
{0, 0, 0, 0},
{0, 0, 0, 0},
{0, 0, 0, 0}
};
if ( solveNQUtil(board, 0) == false )
{
printf("Solution does not exist");
return false;
}
printSolution(board);
return true;
}
// driver program to test above function
int main()
{
solveNQ();
return 0;
}
Output: The 1 values indicate placements of queens
0 0 1 0
1 0 0 0
0 0 0 1
0 1 0 0
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