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StrugglingCoder
StrugglingCoder

Reputation: 5021

Generate a 2d array in spiral form

Given a number say 3 to 4 , I need to generate a 2D array in spiral form and print it. For Example :

If given 3, the 3*3 array generated can be printed like:

7 8 9
6 5 4
1 2 3

Or, given 4, it should be 4*4 array in spiral form

16 15 14 13
9  10 11 12 
8  7  6  5
1  2  3  4

I tried in a psudeo code to push all the numbers in a one single dimensional array.

But I do not how to print them in such a 2D array format.

PSEUDO _ CODE

arr = new Array(val*val);// []
        let pass = 0;
        let j = 0;
        target = val*val; // 9
        while(pass < n) {
            if(pass % 2 === 0) { //pass 0 - 1 2 3 // pass 2 - 7 8 9
                for(let i = j + 1; i >= j+n; i++) {
                    arr.push(i);
                }               
                j = i;
            } else { // pass 1 - 6 5 4
                for(let i = j+n; i >= j+1; i--) {
                    arr.push(i);
                }
                j = i;
            }           
            pass++;
        }

Upvotes: 0

Views: 156

Answers (3)

Saadi Toumi Fouad
Saadi Toumi Fouad

Reputation: 2829

You can do it like this

function a(b) {
  var c = "";
  for(var d = b * b;d > 0; d--) {
    c += d + ((d - 1) % b === 0 ? "\n" : " ");
  }
  return c;
}

console.log(a(2));
console.log(a(3));
console.log(a(4));
console.log(a(5));

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386604

You could calculate the value for a certain position.

const
    getZigZag = length => Array.from(
        { length },
        (_, i) => Array.from(
            { length },
            (_, j) => (length - i) % 2 
                ? (length - i - 1) * length + j + 1
                : (length - i - 1) * length + length - j
        )
    );

getZigZag(3).forEach(a => console.log(...a));
console.log()
getZigZag(4).forEach(a => console.log(...a));

Upvotes: 1

Hassan Imam
Hassan Imam

Reputation: 22534

This could be done using Array.from. First for each row generate number and then join them. The inner array could be joined on ' ', while the outer array could be joined using '\n' after reversing.

const generatePattern = (length) => Array.from({length}, (_, i) => {
  const subArray = Array.from({length}, (_, index) => length*i + index + 1);
  return i % 2 === 0 ? subArray.join(' ') : subArray.reverse().join(' ');
}).reverse().join('\n');

console.log(generatePattern(3));
console.log(generatePattern(4));
console.log(generatePattern(5));
.as-console-wrapper { max-height: 100% !important; top: 0; }

Upvotes: 1

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