Competetive-Programming/NqueenProblem.cpp at master · payal-98/Competetive-Programming · GitHub

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#include<iostream>
using namespace std;
void print(int board[4][4])
{
	for(int i=0;i<4;i++)
	{
		for(int j=0;j<4;j++)
		cout<<board[i][j]<<" ";
		cout<<endl;
	}
}
bool issafe(int board[4][4],int row,int col)
{
	for(int i=0;i<col;i++)
	if(board[row][i])
	return false;

	for(int i=row,j=col;i>=0 && j>=0 ;i--,j--)
	if(board[i][j])
	return false;

	for(int i=row,j=col;i<4 && j>=0 ;i++,j--)
	if(board[i][j])
	return false;

	return true;

}

bool solve(int board[4][4],int col)
{
	if(col==4)
	return true;

	for(int i=0;i<4;i++)
	{
	  	if(issafe(board,i,col))
	  	{
	  		board[i][col]=1;
			  if(solve(board,col+1))
			  return true;

			  board[i][col]=0;
		}
	}
	return false;
}

int main()
{
	int board[4][4] = { {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0},
        {0, 0, 0, 0}
    };

    if ( solve(board, 0) == false )
     {
	   	printf("SOLUTION DOES NOT EXIT");
      	return 0;
	}
 	else
    print(board);
	return 0;
}