#include <stdio.h>
#include <stdlib.h>
#include <string.h>   /* for strcmp */

#define LIFE_YMAX 10
#define LIFE_XMAX 10

int main()
{
	int old[LIFE_YMAX + 2][LIFE_XMAX + 2] = {   /* sorry y before x */
		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},

		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 1, 0, 0, 0, 0, 0, 0, 0, 0,  0},   /* a glider */
		{0,  0, 0, 1, 1, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 1, 1, 0, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},
		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0},

		{0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  0}
	};
	int new[LIFE_YMAX + 2][LIFE_XMAX + 2];
	int generation;
	char buffer[256];
	size_t x, y;     /* loop through all elements in the array */
	int count;
	size_t x1, y1;   /* subscript of each of the 8 neighbors of x, y */

	for (generation = 0;; ++generation) {

		/* Print the matrix. */
		for (y = 1; y <= LIFE_YMAX; ++y) {
			for (x = 1; x <= LIFE_XMAX; ++x) {
				/* sorry y before x */
				putchar(old[y][x] ? 'X' : '.');
			}
			putchar('\n');
		}

		printf("%d: Press c to continue, q to quit, and RETURN.\n",
			generation);
		scanf("%s", buffer);
		if (strcmp(buffer, "c") != 0) {
			break;
		}

		for (y = 1; y <= LIFE_YMAX; ++y) {
			for (x = 1; x <= LIFE_XMAX; ++x) {

				/* How many of the 8 neighbors of element x, y
				are turned on? Don't count the element itself.*/
				count = -old[y][x];

				for (y1 = y - 1; y1 <= y + 1; ++y1) {
					for (x1 = x - 1; x1 <= x + 1; ++x1) {
						count += old[y1][x1];
					}
				}

				/* Law of Survival */
				if (count == 2) {
					new[y][x] = old[y][x];
				}

				/* Law of Birth */
				else if (count == 3) {
					new[y][x] = 1;
				}

				/* Law of Death */
				else {
					new[y][x] = 0;
				}
			}
		}

		/* Copy new into old. */
		for (y = 1; y <= LIFE_YMAX; ++y) {
			for (x = 1; x <= LIFE_XMAX; ++x) {
				old[y][x] = new[y][x];
			}
		}
	}

	return EXIT_SUCCESS;
}