Function N_Queens

CPP/recursion/N_Queens/N_Queens.cpp:67–111

Main recursive function.

// Main recursive function.
bool N_Queens(std::vector<std::vector<int>> &board, int n, int row)
{
    // --> base case
    // When row becomes equal to n
    // means all queens have been placed in the right manner.
    if (row == n)
    {
        // Print the first possible way.
        printBoard(board, n);
        // Endl for printing the next possible board
        // std::cout << std::endl;
        // Return true for returning to main.
        return true;
        // Return false for printing all possibilities.
        // return false;
    }

    // --> recursive case
    for (int column = 0; column < n; ++column)
    {
        // Check if the queen can be placed at the ith row and jth column.
        if (canBePlaced(board, row, column, n))
        {
            // Mark that place as 1.
            board[row][column] = 1;
            // Check for further positions.
            bool remaining_positions = N_Queens(board, n, row + 1);
            if (remaining_positions)
            {
                // If queens can be placed in the remaining positions
                // it means the placing of queens can proceed further.
                // return true
                return true;
            }
            else
            {
                // If queens cannot be placed further in the right way
                // backtrack to the previous position.
                board[row][column] = 0;
            }
        }
    }

    return false;
}

int main()
{