Count Number of Teams LeetCode solution in JavaScript

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// counting bigger / smaller elements
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// if after rating[i] has X bigger elements,
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// and each element has Y bigger elements after them
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// hence total elements that has i < j < k and rating[i] < rating[j] < rating[k]
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// same for the number of smaller elements
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// so the key point here is to know how many elements
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// that smaller and bigger than the current number
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var numTeams = function (rating) {
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  // save total number of elements after i
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  // that smaller than rating[i]
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  let big = new Array(rating.length).fill(0);
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  let n = rating.length;
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  for (let i = 0; i < n - 1; i++) {
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    for (let j = i + 1; j < n; j++) {
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      if (rating[j] > rating[i]) big[i]++;
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    }
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  }
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  let count = 0;
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  for (let i = 0; i < n - 1; i++) {
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    for (let j = i + 1; j < n; j++) {
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      if (rating[j] > rating[i]) count += big[j];
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      // because all elements are unique, so
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      // we don't need to calculate the number of smaller elements
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      // because if there are X bigger elements after rating[i]
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      // then there are (n - i - 1 - X) smaller elements after rating[i]
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      // or small = n - i - 1 - big
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      else count += n - j - 1 - big[j];
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    }
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  }
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  return count;
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};