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class Solution {
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 public:
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  vector<int> xorQueries(vector<int> &arr, vector<vector<int>> &queries) {
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    int n = arr.size();
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    int q = queries.size();
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    vector<int> answer(q, 0);
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    vector<int> prefXor(n, 0);
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    prefXor[0] = arr[0];
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    for (int i = 1; i < n; i++) {
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      prefXor[i] = prefXor[i - 1] ^ arr[i];
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    }
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    for (int i = 0; i < q; i++) {
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      int left = queries[i][0];
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      int right = queries[i][1];
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      if (left == 0)
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        answer[i] = prefXor[right];
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      else
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        answer[i] = prefXor[right] ^ prefXor[left - 1];
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    }
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    return answer;
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  }
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};