/***********************

Conway Game of Life

************************/

#include <stdio.h>

#include <stdlib.h>

#define NI 1000        /* array sizes */

#define NJ 1000

#define NSTEPS 500    /* number of time steps */

int i, j, n, im, ip, jm, jp, ni, nj, nsum, isum;
int **old, **new;
float x;
FILE *outFile;

// doTimeStep(int n);

void doTimeStep(int n){

	/* corner boundary conditions */
	old[0][0] = old[NI][NJ];
	old[0][NJ + 1] = old[NI][1];
	old[NI + 1][NJ + 1] = old[1][1];
	old[NI + 1][0] = old[1][NJ];

	/* left-right boundary conditions */

	for (i = 1; i <= NI; i++){
		old[i][0] = old[i][NJ];
		old[i][NJ + 1] = old[i][1];
	}

	/* top-bottom boundary conditions */

	for (j = 1; j <= NJ; j++){
		old[0][j] = old[NI][j];
		old[NI + 1][j] = old[1][j];
	}

	for (i = 1; i <= NI; i++){
		for (j = 1; j <= NJ; j++){
			im = i - 1;
			ip = i + 1;
			jm = j - 1;
			jp = j + 1;

			nsum = old[im][jp] + old[i][jp] + old[ip][jp]
				+ old[im][j] + old[ip][j]
				+ old[im][jm] + old[i][jm] + old[ip][jm];

			switch (nsum){

			case 3:
				new[i][j] = 1;
				break;

			case 2:
				new[i][j] = old[i][j];
				break;

			default:
				new[i][j] = 0;
			}
		}
	}

	/* copy new state into old state */

	for (i = 1; i <= NI; i++){
		for (j = 1; j <= NJ; j++){
			old[i][j] = new[i][j];
		}
	}
}

int main(int argc, char *argv[]) {



  

  /* allocate arrays */

  ni = NI + 2;  /* add 2 for left and right ghost cells */
  nj = NJ + 2;
  old = malloc(ni*sizeof(int*));
  new = malloc(ni*sizeof(int*));

  for(i=0; i<ni; i++){
    old[i] = malloc(nj*sizeof(int));
    new[i] = malloc(nj*sizeof(int));
  }

/*  initialize elements of old to 0 or 1 */

  for(i=1; i<=NI; i++){
    for(j=1; j<=NJ; j++){
      x = rand()/((float)RAND_MAX + 1);
      if(x<0.5){
	old[i][j] = 0;
      } else {
	old[i][j] = 1;
      }
    }
  }

  /*  time steps */
  for(n=0; n<NSTEPS; n++){
	  doTimeStep(n);
  }

  /*  Iterations are done; sum the number of live cells */
  isum = 0;
  for(i=1; i<=NI; i++){
    for(j=1; j<=NJ; j++){
      isum = isum + new[i][j];
    }
  }
  printf("\nNumber of live cells = %d\n", isum);

  //getchar(); /*To get the console window to stay open!*/

  return 0;
}