Creating a binary spiral array of specific size in JavaScript

JavascriptWeb DevelopmentFront End Technology

Problem

We are required to write a JavaScript function that takes in a number n. Our function should construct and return an array of N * N order (2-D array), in which the 1s take all the spiralling positions starting from [0, 0] and all the 0s take non-spiralling positions.

Therefore, for n = 5, the output will look like −

[
   [ 1, 1, 1, 1, 1 ],
   [ 0, 0, 0, 0, 1 ],
   [ 1, 1, 1, 0, 1 ],
   [ 1, 0, 0, 0, 1 ],
   [ 1, 1, 1, 1, 1 ]
]

Example

Following is the code −

 Live Demo

const num = 5;
const spiralize = (num = 1) => {
   const arr = [];
   let x, y;
   for (x = 0; x < num; x++) {
      arr[x] = Array.from({
         length: num,
      }).fill(0);
   }
   let left = 0;
   let right = num;
   let top = 0;
   let bottom = num;
   x = left;
   y = top;
   let h = Math.floor(num / 2);
   while (left < right && top < bottom) {
      while (y < right) {
         arr[x][y] = 1;
         y++;
      }
      y--;
      x++;
      top += 2;
      if (top >= bottom) break;
      while (x < bottom) {
         arr[x][y] = 1;
         x++;
      }
      x--;
      y--;
      right -= 2;
      if (left >= right) break;
      while (y >= left) {
         arr[x][y] = 1;
         y--;
      }
      y++;
      x--;
      bottom -= 2;
      if (top >= bottom) break;
      while (x >= top) {
         arr[x][y] = 1;
         x--;
      }
      x++;
      y++;
      left += 2;
   }
   if (num % 2 == 0) arr[h][h] = 1;
   return arr;
};
console.log(spiralize(num));

Output

Following is the console output −

[
   [ 1, 1, 1, 1, 1 ],
   [ 0, 0, 0, 0, 1 ],
   [ 1, 1, 1, 0, 1 ],
   [ 1, 0, 0, 0, 1 ],
   [ 1, 1, 1, 1, 1 ]
]
raja
Published on 17-Apr-2021 12:01:59
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