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var tupleSameProduct = function (nums) {
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  let tupleCount = 0;
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  let products = {}; // we'll keep track of how many times we've seen a given product before
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  for (let a = 0; a < nums.length; a++) {
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    for (let b = a + 1; b < nums.length; b++) {
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      let product = nums[a] * nums[b];
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      if (products[product]) {
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        // we've seen at least one other pair of numbers with the same product already
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        tupleCount += 8 * products[product]; // multiply by 8 because for any 4 numbers there are 8 permutations
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        products[product] += 1; // increment the count, if we see this product again there are even more possible tuple combinations
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      } else {
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        products[product] = 1; // mark as seen once
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      }
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    }
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  }
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  return tupleCount;
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};