411 REFERENCE · Wikibooks
Algorithm Implementation/Simulation/Conway's Game of Life
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Conway's Game of Life is a cellular automaton with two states for each cell. The following implementation(s) calculate the next generation.
Java
import java.io.*;
public class GOL{
public static String boardToString (boolean[][] board, int xsize, int ysize){
StringBuffer sb= new StringBuffer(); // used to print out the board at the end
for (int i=0;i<xsize;i++){
for (int j=0;j<ysize;j++){
if (board [i][j]){
sb.append('*');
}else{
sb.append(' ');
}
}
sb.append("\n");
}
return sb.toString();
}
public static boolean[][] strToBoolMatrix (String str, int xsize, int ysize){
boolean [][] board = new boolean[xsize][ysize]; // converts an input string into the
for (int i=0;i<xsize; i++){ // boolean[][] used internally
for (int j=0; j<ysize; j++){
board[i][j] = str.charAt((i*xsize)+j) != '0';
}
}
return board;
}
public static int mod (int x, int m){ // deals with java's % returning negative vals for
m = Math.abs(m); // negative inputs
return (x % m + m) % m;
}
public static int getNeighborCount(boolean[][] board, int x, int y, int xsize, int ysize){
int nc = 0; // this function rather messily counts up the neighbors
if (board[mod(x+1,xsize)][y]){
nc++;
}
if (board[mod(x+1,xsize)][mod(y+1, ysize)]){
nc++;
}
if (board[x][mod(y+1,ysize)]){
nc++;
}
if (board[x][mod(y-1,ysize)]){
nc++;
}
if (board[mod(x+1,xsize)][mod(y-1,ysize)]){
nc++;
}
if (board[mod(x-1,xsize)][y]){
nc ++;
}
if (board[mod(x-1,xsize)][mod(y-1,ysize)]){
nc ++;
}
if (board[mod(x-1,xsize)][mod(y+1,ysize)]){
nc ++;
}
return nc;
}
public static boolean getDot(boolean[][] board, int x, int y, int xsize, int ysize){
// this function applies the rules of the game on one square
return board[x][y] && getNeighborCount(board, x,y,xsize,ysize) == 2
|| getNeighborCount(board,x,y,xsize,ysize) == 3;
}
public static void main(String[] args) throws java.io.FileNotFoundException, java.io.IOException{
int xsize = Integer.parseInt(args[0]); // takes board size off command line
int ysize = Integer.parseInt(args[1]);
int gen = Integer.parseInt(args[2]); // number of generations
FileReader fr = new FileReader(args[3]); // will read in board from a file
BufferedReader br= new BufferedReader(fr);
StringBuffer sb = new StringBuffer();
String line = new String(br.readLine());
while(line != null){ // reading file
sb.append(line);
line = br.readLine();
}
String s = sb.toString();
boolean[][] board = strToBoolMatrix(s,xsize,ysize); // this is the game board
for (int i=0; i<gen; i++){ // loops through the generations
boolean[][] next = new boolean[xsize][ysize]; // empty board
for (int j=0;j<xsize;j++){ // loops through x-axis for computing the next generation
for (int k=0; k< ysize; k++){ // loops through y-axis
next[j][k] = getDot(board,j,k,xsize,ysize);
}
}
board = next; // use the 'next' array as the new 'board' array
}
System.out.println(boardToString(board,xsize,ysize)); // prints the board
}
}