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class Solution {
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  public int[] xorQueries(int[] arr, int[][] queries) {
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    int[] ans = new int[queries.length];
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    int[] xor = new int[arr.length];
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    xor[0] = arr[0];
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    // computing prefix XOR of arr
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    for (int i = 1; i < arr.length; i++) {
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      xor[i] = arr[i] ^ xor[i - 1];
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    }
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    for (int i = 0; i < queries.length; i++) {
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      // if query starts from something other than 0 (say i), then we XOR all values from arr[0] to
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      // arr[i-1]
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      if (queries[i][0] != 0) {
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        ans[i] = xor[queries[i][1]];
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        for (int j = 0; j < queries[i][0]; j++) {
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          ans[i] = arr[j] ^ ans[i];
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        }
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      }
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      // if start of query is 0, then we striaght up use the prefix XOR till ith element
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      else ans[i] = xor[queries[i][1]];
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    }
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    return ans;
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  }
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}