K-th Symbol in Grammar LeetCode solution in JavaScript

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/**
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 * @param {number} n
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 * @param {number} k
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 * @return {number}
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 */
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var kthGrammar = function (n, k) {
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  if (n == 1 && k == 1) {
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    return 0;
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  }
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  const mid = Math.pow(2, n - 1) / 2;
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  if (k <= mid) {
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    return kthGrammar(n - 1, k);
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  } else {
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    return kthGrammar(n - 1, k - mid) == 1 ? 0 : 1;
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  }
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};