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class knightTour
{
public:
knightTour(int = 0);
bool canPlaceKnight(int&, int&, int); //function to determine if knight can be placed in a particular cell on chess board
bool moveWithinBounds(int, int, int); //function to determine if knight move is within the bounds of the chess board
bool traceKnightTour(int, int); //function to trace the path of the knight; all cells must be visited, each at most once
void printKnightTour();
pair <int, int> indexToKnightMoveConverter(int);
private:
int noOfCellsFilled;
int boardSize;
int** chessBoard;
};
bool knightTour::traceKnightTour(int row, int col)
{
if (noOfCellsFilled < boardSize*boardSize)
{
if (noOfCellsFilled == 0)
{
chessBoard[row][col] = 1;
++noOfCellsFilled;
}
for (int i = 0; i < 8; i++)
{
if (canPlaceKnight(row, col, i)) //determines the rowcolumn coordinates of knight's cell
{
static queue<pair<int,int> > q; //queue to hold rowcolumn coordinates of the current and last cell entries
q.push(make_pair(row, col));
if (q.size() > 2) //ensuring the queue size is 2
q.pop();
showQueueContents(q); //function to display the contents of the queue
chessBoard[row][col] = ++noOfCellsFilled; //fill cell with corresponding number
if (traceKnightTour(row, col)) //recursive call
return true;
chessBoard[row][col] = 0; //backtracking
showQueueContents(q); //displaying queue contents after recursive call
pair<int, int> temp;
if (!q.empty())
temp = q.front(); //since we are backtracking, retrieve rowcolumn pair of last cell filled from the queue
row = temp.first; //grab the rowcolumn coordinates of the last cell filled
col = temp.second;
cout<<"noOfCellsFilled = "<<noOfCellsFilled<<endl;
noOfCellsFilled;
}
}
return false;
}
else //all the cells of the chess board are filled
return true;
}
 