Greatest Sum Divisible by Three LeetCode solution in C++

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class Solution {
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 public:
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  int maxSumDivThree(vector<int> &nums) {
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    vector<int> twos = {(int)1e4 + 1, (int)1e4 + 1}, ones = {(int)1e4 + 1, (int)1e4 + 1};
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    int res = 0;
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    for (int i : nums) {
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      if (i % 3 == 2) {
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        if (i <= twos[0]) {
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          twos[1] = twos[0], twos[0] = i;
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        } else if (i < twos[1])
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          twos[1] = i;
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      } else if (i % 3 == 1) {
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        if (i <= ones[0]) {
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          ones[1] = ones[0], ones[0] = i;
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        } else if (i < ones[1])
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          ones[1] = i;
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      }
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      res += i;
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    }
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    if (res % 3 == 2)
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      return max(res - twos[0], res - ones[0] - ones[1]);
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    else if (res % 3 == 1)
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      return max(res - ones[0], res - twos[0] - twos[1]);
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    return res;
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  }
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};