Largest 1-Bordered Square LeetCode solution in JavaScript

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var largest1BorderedSquare = function (grid) {
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  let m = grid.length,
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    n = grid[0].length;
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  let top = Array(m)
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    .fill(0)
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    .map(() => Array(n).fill(0));
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  let left = Array(m)
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    .fill(0)
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    .map(() => Array(n).fill(0));
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  for (let i = 0; i < m; i++) {
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    for (let j = 0; j < n; j++) {
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      if (grid[i][j] === 1) {
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        left[i][j] = j > 0 ? left[i][j - 1] + 1 : 1;
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        top[i][j] = i > 0 ? top[i - 1][j] + 1 : 1;
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      }
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    }
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  }
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  let ans = 0;
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  for (let i = 0; i < m; i++) {
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    for (let j = 0; j < n; j++) {
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      let size = Math.min(top[i][j], left[i][j]);
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      for (let k = size; k > 0; k--) {
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        let bottomLeftTop = top[i][j - k + 1];
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        let topRightLeft = left[i - k + 1][j];
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        if (bottomLeftTop >= k && topRightLeft >= k) {
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          ans = Math.max(ans, k * k);
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          break;
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        }
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      }
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    }
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  }
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  return ans;
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};