conway

#include <stdio.h>
#include <stdlib.h>

#define WIDTH 30
#define HEIGHT 20

int
count_neighbour(int **grid, size_t h, size_t w)
{
        int c = 0;
        int i, j;
        for (i = -1; i < 2; i++) {
                for (j = -1; j < 2; j++) {
                        if ((i == 0 && j == 0) || (h == 0 && i == -1)
                            || (w == 0 && j == -1) || (h == HEIGHT-1 && i == 1)
                            || (w == WIDTH-1 && j == 1))
                                continue;
                        c += (grid[h+i][w+j] == 1 || grid[h+i][w+j] == 2);
                }
        }
        return c;
}

void
progress(int **grid)
{
        size_t h, w;
        int c;

        for (h = 0; h < HEIGHT; h++) {
                for (w = 0; w < WIDTH; w++) {
                        c = count_neighbour(grid, h, w);
                        if (grid[h][w] == 0 && c == 3)
                                grid[h][w] = 3;
                        else if (grid[h][w] == 1 && !(c == 2 || c == 3))
                                grid[h][w] = 2;
                }
        }

        for (h = 0; h < HEIGHT; h++)
                for (w = 0; w < WIDTH; w++)
                        grid[h][w] &= 1;
}

void
print_grid(int **grid)
{
        size_t h, w;
        for (h = 0; h < HEIGHT; h++) {
                for (w = 0; w < WIDTH; w++)
                        printf("%c", (grid[h][w] ? 'o' : ' '));
                printf("\n");
        }
        printf("------------------------------\n");
}

int
main(void)
{
        int **grid = malloc(sizeof(int) * HEIGHT);
        for (int i = 0; i < HEIGHT; i++) {
                grid[i] = malloc(sizeof(int) * WIDTH);
                for (int j = 0; j < WIDTH; j++)
                        grid[i][j] = arc4random_uniform(2);
        }

        print_grid(grid);
        for (;;) {
                getchar();
                progress(grid);
                print_grid(grid);
        }
}