Minimum Average Difference LeetCode solution in C++

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class Solution {
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 public:
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  int minimumAverageDifference(vector<int> &nums) {
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    int n(size(nums)), minAverageDifference(INT_MAX), index;
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    long long sumFromFront(0), sumFromEnd(0);
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    for (auto &num : nums) sumFromEnd += num;
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    for (int i = 0; i < n; i++) {
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      sumFromFront += nums[i];
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      sumFromEnd -= nums[i];
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      int a = sumFromFront / (i + 1); // average of the first i + 1 elements.
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      int b =
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          (i == n - 1) ? 0 : sumFromEnd / (n - i - 1); // average of the last n - i - 1 elements.
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      if (abs(a - b) < minAverageDifference) {
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        minAverageDifference = abs(a - b);
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        index = i;
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      }
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    }
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    return index;
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  }
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};