How to stop running loop when identical array is found?

Question

I am making a tic tac toe game. Each square on the board has an index from 0 to 8. To check the winner, I have a two-dimensional array winningPlays that contains all potential winning combinations. I have two arrays that contain plays by Xs or by Os - xPlays and oPlays, respectively. After sorting xPlays, I want to compare it to winningPlaysto see if any of the arrays match. If they do, I want to console.log('X wins'). I can't seem to find a way to execute the console.log at the right time to determine the winner. Here is the piece of problem code:

const winningPlays = [
        [0,1,2], //across top
        [3,4,5], //across middle
        [6,7,8], //across bottom
        [0,3,6], //left down
        [1,4,7], //middle down
        [2,5,8], //right down
        [0,4,8], //top left to bottom right
        [2,4,6] // top right to bottom left
    ]; //length == 8

    function checkForWinner() {
        for(let i = 0; i < winningPlays.length; i++){
            for(let j = 0; j < winningPlays[i].length; j++){
                if (xPlays.length < 3) {
                    return;
                } else if (winningPlays[i][j] !== xPlays[j]) {
                    console.log(winningPlays[i][j])
                    console.log(xPlays[j])
                    return;
                }
                console.log('win')  // executes every time that xPlays.length >= 3
            }
        } 
    };

And here is a link to my codepen draft: https://codepen.io/CDLWebDev/pen/gOawjvE

That way of checking the winner doesn't seem too great to be honest. — Robo Robok
– Robo Robok, Commented Apr 20, 2020 at 22:04
You can write a function checking if a player won. Your best friend will be the for loop. — Robo Robok
– Robo Robok, Commented Apr 20, 2020 at 22:08

Barmar · Accepted Answer · 2020-04-20 22:09:37Z

2

You have several problems.

First, you return from the function as soon as you find a mismatch, but a later element of winningPlays could match.

Second, you're expecting xPlays to exactly match one of the winningPlays elements. But X could have additional plays. For instance, if xPlays = [2, 3, 4, 5], that should match[3, 4, 5]. What you really want to test is if all the elements of one of thewinningPlayselements are included inxPlays`, they don't have to have the same index.

function checkForWinner() {
  if (xPlays.length < 3) {
    return;
  }
  for (let i = 0; i < winningPlays.length; i++) {
    let win = true;
    for (let j = 0; j < winningPlays[i].length; j++) {
      if (!xPlays.includes(winningPlays[i][j])) {
        win = false;
        break;
      }
    }
    if (win) {
      console.log('win');
      break;
    }
  }
}

answered Apr 20, 2020 at 22:09

Barmar

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1 Comment

Carl D'Oleo-Lundgren Over a year ago

This is a wonderful and elegant solution! In actuality, I had realized that I would have the second problem eventually, but I was trying to break them apart and solve them one at a time. But this solves both issues in one fell swoop. Thanks very much, @Barmar

Manish Sundriyal · Accepted Answer · 2020-04-20 22:10:44Z

0

Go through each sub-array
Check if all the items of that subArray are present in players array

function checkWinner() {
    return winningPlays.some(list => {
        return list.every(item => {
            return xPlays.includes(item);
        });
    });
}

answered Apr 20, 2020 at 22:10

Manish Sundriyal

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Comments

Linh Nguyen · Accepted Answer · 2020-04-20 22:23:27Z

0

I would make it simpler by doing like following

const winningPlays = [
    "0,1,2", //across top
    "3,4,5", //across middle
    "6,7,8", //across bottom
    "0,3,6", //left down
    "1,4,7", //middle down
    "2,5,8", //right down
    "0,4,8", //top left to bottom right
    "2,4,6" // top right to bottom left
]; //length == 8

function checkForWinner(xPlays) {
    var convertXPlays = xPlays.toString(); //if there are spaces in your array, make sure to remove it
    if (winningPlays.indexOf(convertXPlays) > -1)
    {
       console.log('win!');
    }
};

edited Apr 20, 2020 at 22:23

answered Apr 20, 2020 at 22:17

Linh Nguyen

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