life game

#include <iostream>

using namespace std;
const int SIZE = 20;
const string CELL_SIGN = "X";

void display_board(int board[SIZE][SIZE])
{
    for (int row = 0; row < SIZE; row++)
    {
        for (int col = 0; col < SIZE; col++)
        {
            if (board[row][col] == 0)
            {
                cout << " ";
            }
            else
            {
                cout << CELL_SIGN;
            }
        }
        cout << endl;
    }
}

int count_neighbours(int board[SIZE][SIZE], int row, int col)
{
    int neighbours = 0;

    int up, down, left, right, vertical_center, horizontal_center;

    if (row == 0)
    {
        up = SIZE-1;
        vertical_center = row;
        down = row + 1;
    }
    else if (row == SIZE - 1)
    {
        up = row - 1;
        vertical_center = row;
        down = 0;
    }
    else
    {
        up = row - 1;
        vertical_center = row;
        down = row + 1;
    }

    if(col == 0)
    {
        left = SIZE-1;
        horizontal_center = col;
        right = col + 1;
    }
    else if (col == SIZE-1)
    {
        left = col-1;
        horizontal_center = col;
        right = 0;
    }
    else
    {
        left = col-1;
        horizontal_center = col;
        right = col + 1;
    }

    neighbours += board[up][left];
    neighbours += board[up][horizontal_center];
    neighbours += board[up][right];
    neighbours += board[vertical_center][left];
    neighbours += board[vertical_center][right];
    neighbours += board[down][left];
    neighbours += board[down][horizontal_center];
    neighbours += board[down][right];

    return neighbours;
}

void generation(int board[SIZE][SIZE])
{
    int new_board[SIZE][SIZE] = {0};

    for (int row = 0; row < SIZE; row++)
    {
        for (int col = 0; col < SIZE; col++)
        {
            int neighbours= count_neighbours(board, row, col);

            if (board[row][col] == 1 && ( neighbours < 2 || neighbours > 3))
            {
                new_board[row][col] = 0;
            }
            else if (board[row][col] == 1)
            {
                new_board[row][col] = 1;
            }
            else if (board[row][col] == 0 && neighbours == 3)
            {
                new_board [row][col] = 1;
            }

        }
    }

    for (int row = 0; row < SIZE; row++)
    {
        for (int col = 0; col < SIZE; col++)
        {
            board[row][col] = new_board[row][col];
        }
    }

}

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

    board[9][8] = 1;
    board[9][10] = 1;
    board[10][10] = 1;
    board[10][9] = 1;
    board[11][9] = 1;


    display_board(board);
    generation(board);
    display_board(board);

}