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class Solution {
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 public:
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  int subsetXORSum(vector<int> &nums) {
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    int ans = 0;
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    for (int i = 0; i < 32; i++) {
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      int mask = 1 << i;
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      int count = 0;
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      for (int j = 0; j < nums.size(); j++) {
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        if (nums[j] & mask) count++;
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      }
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      if (count) {
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        ans += mask * (1 << (count - 1)) * (1 << (nums.size() - count));
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      }
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    }
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    return ans;
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  }
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};