Counting Bits LeetCode solution in C++

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class Solution {
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 private:
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  int countones(int n) {
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    int count = 0;
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    while (n) {
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      count++;
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      n = n & (n - 1);
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    }
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    return count;
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  }
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 public:
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  vector<int> countBits(int n) {
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    vector<int> ans;
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    for (int i = 0; i <= n; i++) {
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      int x = countones(i);
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      ans.push_back(x);
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    }
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    return ans;
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  }
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};