How to optimize this code to make it faster

Question

I am a really really new noobie high school student in java and we're currently optimizing a project but I'm stuck now. I think I've down everything I can do. Below are my 3 classes. PS, These codes print out the time spent in while loop and I'm trying to get it down to less than 1 sec on my computer. It's running between 1.49 and 1.38 currently.

main:

public class code {
    public static void main(String[] args) {
        int numRows = 30;
        int numCols = 30;
        int start = 31;
        int exit = 868;
        int numKittens = 30_000;
        KittenBox box = new KittenBox(numRows, numCols, start, exit, 
                  numKittens);
        double a = 10;
        box.play();
    }
}

kitten.java:

import java.util.SplittableRandom;

public class Kitten {

private int rows;
private int columns;
public int square;
private SplittableRandom a;

public Kitten(int rows, int columns, int square) {
    this.rows = rows;
    this.columns = columns;
    this.square = square;
    a = new SplittableRandom();
}

public int move() {
    int i = a.nextInt(1, 5);
    return (i == 1 && (!(this.square < columns))) ? 
            this.square -= rows : ((i == 2 && (!(this.square >= columns * 
            (rows - 1)))) ? this.square += rows : ((i == 3 && (!(this.square
            % rows == 0))) ? this.square -= 1 : ((!(this.square % rows == 
            rows - 1)) ? this.square += 1 : this.square)));
}

}

kittenbox.java:

public class KittenBox {

    private ArrayList<Kitten> kitten;
    private int numRows;
    private int numCols;
    private int start;
    private int exit;
    private int numKittens;

    public KittenBox(int numRows, int numCols, int start, int exit, int numKittens) {
        this.numRows = numRows;
        this.numCols = numCols;
        this.start = start;
        this.exit = exit;
        this.numKittens = numKittens;
        kitten = new ArrayList<>();

    }
    public void play() {
        for (int i = 0; i < numKittens; i++) {
            kitten.add(new Kitten(numRows, numCols, start));
        }
        long startTime = System.nanoTime();
        while (!kitten.isEmpty()) {
            for (int i = 0; i < kitten.size(); i++) {
                kitten.get(i).move();
                if (kitten.get(i).square == exit) {
                    kitten.remove(i);
                }
            }
        }
        long endTime = System.nanoTime();
        System.out.format("Kittens took %f seconds to escape.\n",
                (endTime - startTime) / 1000000000.0);
    }
}

but I still can't speed my code up to the benchmark. is there any way that's faster?

thanks a lot.

Are you sure that there is nothing else in your code slowing it down? Library methods like this are usually well optimized. Maybe provide more code because there is a change you are focusing on the wrong line. — Sunny, Feb 14 '20 at 05:30
Have you profiled your application to find the bottleneck or is it just your guess that this specific line is causing your app to miss the benchmark (which one?)? — Nicktar, Feb 14 '20 at 06:50

score 0 · Answer 1 · answered Feb 14 '20 at 05:25

You can opt for:

Math.random() // it has reliable efficiency.

you can refer following program:

        int max = 5; 
        int min = 1; 
        int range = max - min + 1; 

        // generate random numbers within 1 to 10 
        for (int i = 0; i < max; i++) { 
            int rand = (int)(Math.random() * range) + min; 

            // Output is different everytime this code is executed 
            System.out.println(rand); 
        }

score 0 · Answer 2 · answered Feb 14 '20 at 05:26

0

Not sure how fast this is, but you could try this

int randomNumber = (int)(Math.random() * range_size + starting_num);
int one_to_four = (int)(Math.random() * 4 + 1);

answered Feb 14 '20 at 05:26

loganrussell48

1,656
3
15
23

1

https://stackoverflow.com/questions/5292312/is-this-method-faster-than-math-random/5292374 – Pramod S. Nikam Feb 14 '20 at 05:27

score 0 · Answer 3 · answered Feb 21 '20 at 14:42

Your problem is most likely that this terrible mess of a function you call move() does not quite work the way you think it works, and so it is causing kittens to reach 'exit' a lot less frequently than you think they would.

The way this question is worded, this should be enough to help you get on your way. (Besides, it appears to be homework, and for homework we tend to point to solutions without providing actual solutions.)

Before anyone can help you any more with this, you are going to have to rewrite that move() method to make it understandable by human beings.

Hint 1: use a switch() statement.
Hint 2: add a default: cause to your switch statement, which, if reached, throws an exception. This way you will know you are not generating numbers that are never handled.

How to optimize this code to make it faster

3 Answers3

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