HELP game of life array

Question

Zac_3 0 Newbie Poster

8 Years Ago

I got the program to run, but the output is not the way it should be and I don't know where I went wrong.

The output is supposed to look like this:
Sample Input
6 8
7
3 8
3 8
Sample Output

- - - - -
@ @ @ - - - -
@ @ @ @ - @ -
- - @ @ - @ -
@ - @ - @ @ -
- - - - -
- - - - -
@ @ @ @ - - -
@ @ @ @ @ - -
@ @ @ @ @ @ -
- @ @ @ @ @ -
- - - - -
- - - - -
@ @ @ @ @ - -
@ - - @ @ @ -
@ @ - - @ @ -
@ @ @ @ @ @ -
- - - - -
- - - - -
@ @ @ @ @ @ -
@ @ @ @ @ @ -
@ @ @ @ @ @ -
@ @ @ @ @ @ -
- - - - -
- - - - -
@ @ @ @ @ @ -
@ - - - - @ -
@ - - - - @ -
@ @ @ @ @ @ -
- - - - -
- - - - -
@ @ @ @ @ @ -
@ @ @ @ @ @ -
@ @ @ @ @ @ -
@ @ @ @ @ @ -

import java.util.Random;
import java.util.Scanner;

public static void main(String[] args) {

    Scanner console = new Scanner(System.in); 
    System.out.println(" ");
    int rows = console.nextInt(); 

    System.out.println(" ");
    int columns = console.nextInt();

    System.out.println(" ");
    long seed = console.nextLong(); 

    int birthLow = console.nextInt(); 

    int birthHigh = console.nextInt(); 

    int liveLow = console.nextInt();

    int liveHigh = console.nextInt(); 

    boolean myMatrix[][] = new boolean[rows][columns]; 
    array(myMatrix, rows, columns, seed); 
    printArray(myMatrix, rows, columns); 

    System.out.println();

    for(int i=0; i<4; i++) {
        alterMatrix(myMatrix, rows, columns, birthLow, birthHigh, liveLow, liveHigh);
        printArray(myMatrix, rows, columns);
        System.out.println();
    }
}

//------------------------------------------------------------------------------------------
public static void array(boolean[][] Matrix, int rows, int columns,
long seed) {

    Random generator = new Random(seed); 
    for (int i = 1; i < rows - 1; i++) {
        for (int j = 1; j < columns - 1; j++) {

            boolean x = generator.nextBoolean();
            if (!x) {
                Matrix[i][j] = false;
            } else {
                Matrix[i][j] = true;
            }
        }
    }
}

//-----------------------------------------------------------------------------------------------
// Prints the array
public static void printArray(boolean[][] Matrix, int rows, int columns) {

    for (int k = 0; k < rows; k++) {
        for (int m = 0; m < columns; m++) {
            if (!Matrix[k][m]) {
                System.out.print("- ");
            } else {
                System.out.print("@ ");
            }
        }
        System.out.println();
    }
}

//---------------------------------------------------------------------------------------------------------------------
public static void alterMatrix(boolean[][] myMatrix, int rows,
int columns, int birthLow, int birthHigh, int liveLow, int liveHigh) {

    boolean[][] myNewMatrix = myMatrix.clone();
    for (int row = 0; row < myMatrix.length; row++) {
        myNewMatrix[row] = myNewMatrix[row].clone();

        for (int i = 1; i < rows - 1; i++) {
            for (int j = 1; j < columns - 1; j++) {


                if (!myMatrix[i][j]) {
                    int counter = 0;
                    if (myMatrix[i - 1][j - 1] == true) {
                        counter = counter + 1;
                    } if (myMatrix[i - 1][j] == true) {
                        counter = counter + 1;
                    } if (myMatrix[i - 1][j + 1] == true) {
                        counter = counter + 1;
                    } if (myMatrix[i][j - 1] == true) {
                        counter = counter + 1;
                    } if (myMatrix[i][j + 1] == true) {
                        counter = counter + 1;
                    } if (myMatrix[i + 1][j + 1] == true) {
                        counter = counter + 1;
                    } if (myMatrix[i + 1][j - 1] == true) {
                        counter = counter + 1;
                    } if (myMatrix[i + 1][j] == true) {
                        counter = counter + 1;
                    } else {

                    } if (counter >= birthLow && counter <= birthHigh) {
                        myNewMatrix[i][j] = true;
                    }

                } else {

                    int counter2 = 0;

                    if (myMatrix[i - 1][j - 1] == true) {
                        counter2 = counter2 + 1;
                    } if (myMatrix[i - 1][j] == true) {
                        counter2 = counter2 + 1;
                    } if (myMatrix[i - 1][j + 1] == true) {
                        counter2 = counter2 + 1;
                    } if (myMatrix[i][j - 1] == true) {
                        counter2 = counter2 + 1;
                    } if (myMatrix[i][j + 1] == true) {
                        counter2 = counter2 + 1;
                    } if (myMatrix[i + 1][j + 1] == true) {
                        counter2 = counter2 + 1;
                    } if (myMatrix[i + 1][j - 1] == true) {
                        counter2 = counter2 + 1;
                    } if (myMatrix[i + 1][j] == true) {
                        counter2 = counter2 + 1;
                    }

                    if (counter2 >= liveHigh || counter2 <= liveLow) {
                        myNewMatrix[i][j] = false;
                    } else {

                    }
                }
            }
        }
    }
}

}

java print

Edited 8 Years Ago by Zac_3

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3 Replies
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Latest Post 8 Years Ago Latest Post by JamesCherrill

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JamesCherrill 4,733 Most Valuable Poster

8 Years Ago

<edit> - removed incorrect comment </edit>

In alterMatrix you create and populate myNewMatrix but you never do anything with it.

Edited 8 Years Ago by JamesCherrill

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stultuske 1,116 Posting Maven Featured Poster · Answer 1 · 2016-02-01T08:33:35+00:00

Can't you refactor this bit?

if (myMatrix[i - 1][j - 1] == true) { counter2 = counter2 + 1;
} if (myMatrix[i - 1][j] == true) {counter2 = counter2 + 1;
} if (myMatrix[i - 1][j + 1] == true) { counter2 = counter2 + 1;
} if (myMatrix[i][j - 1] == true) { counter2 = counter2 + 1;
 } if (myMatrix[i][j + 1] == true) {counter2 = counter2 + 1;
 } if (myMatrix[i + 1][j + 1] == true) {counter2 = counter2 + 1;
 } if (myMatrix[i + 1][j - 1] == true) {counter2 = counter2 + 1;
 } if (myMatrix[i + 1][j] == true) {counter2 = counter2 + 1;
 }

First refactoring: remove all the == true parts. checking if 'true == true' is almost as efficient as just checking if true it does, however, increase the chance for typo's.
if ( myMatrix[i][j] = true) for instance, would give wrong results if the original value for myMatrix[i][j] was false.

So, this would lead to:

if (myMatrix[i - 1][j - 1] ) { counter2 = counter2 + 1;
} if (myMatrix[i - 1][j] ) {counter2 = counter2 + 1;
} if (myMatrix[i - 1][j + 1] ) { counter2 = counter2 + 1;
} if (myMatrix[i][j - 1] ) { counter2 = counter2 + 1;
 } if (myMatrix[i][j + 1] ) {counter2 = counter2 + 1;
 } if (myMatrix[i + 1][j + 1] ) {counter2 = counter2 + 1;
 } if (myMatrix[i + 1][j - 1] ) {counter2 = counter2 + 1;
 } if (myMatrix[i + 1][j]) {counter2 = counter2 + 1;
 }

next recommendation: you are repeating a lot of code, why not just using an iteration?

for ( int a = i - 1; a <= i+1; i++){
  if ( myMatrix[a][j-1] || myMatrix[a][j+1] || 
      (a == i && myMatrix[a][j])){ 
          counter2 += 1; 
  }
}

In the end, this will be a lot easier to maintain comparing to all the if blocks.

JamesCherrill 4,733 Most Valuable Poster Team Colleague Featured Poster · Answer 2 · 2016-02-01T09:18:58+00:00

Using an iteration:
Life is very compute intensive when running interesting-sized simulations, so the alterMatrix logic can be time-critical.
When I did this some years ago (!) I tried it both ways

   private int getNeighbourCount(int x, int y) {
      int count = 0;
      if ((grid[x - 1][y - 1])) count++;
      if ((grid[x - 1][y])) count++;
      if ((grid[x - 1][y + 1])) count++;
      if ((grid[x][y - 1])) count++;
      if ((grid[x][y + 1])) count++;
      if ((grid[x + 1][y - 1])) count++;
      if ((grid[x + 1][y])) count++;
      if ((grid[x + 1][y + 1])) count++;
      return count;
   }

   private int getNeighbourCount2(int x, int y) {
      int count = 0;
      for (int xx = x - 1; xx <= x + 1; xx++) {
         for (int yy = y - 1; yy <= y + 1; yy++) {
            if (grid[xx][yy]) count++;
         }
      }
      if (grid[x][y]) count--; // don't count the target cell
      return count;
   }

Against my expectations the first version was 2 1/2 times faster than the second.

HELP game of life array

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