Distribute Repeating Integers LeetCode solution in JavaScript

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var canDistribute = function (nums, quantity) {
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  quantity.sort((a, b) => b - a);
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  let freq = {},
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    flag = false;
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  for (let num of nums) freq[num] = (freq[num] || 0) + 1;
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  let set = Object.keys(freq),
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    n = set.length,
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    k = quantity.length;
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  let rec = (prefix) => {
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    if (prefix.length == k || flag == true) return (flag = true);
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    for (let i = 0; i < n; i++) {
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      freq[set[i]] -= quantity[prefix.length];
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      prefix.push(set[i]);
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      if (freq[set[i]] >= 0) rec(prefix);
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      prefix.pop();
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      freq[set[i]] += quantity[prefix.length];
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    }
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  };
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  rec([]);
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  return flag;
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};