Combinations LeetCode solution in C++

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class Solution {
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 public:
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  void solve(vector<int> arr, vector<vector<int>> &ans, vector<int> &temp, int k, int x) {
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    if (temp.size() == k) {
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      ans.push_back(temp);
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      return;
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    }
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    if (x >= arr.size()) return;
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    for (int i = x; i < arr.size(); i++) {
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      temp.push_back(arr[i]);
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      solve(arr, ans, temp, k, i + 1);
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      temp.pop_back();
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    }
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  }
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  vector<vector<int>> combine(int n, int k) {
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    vector<vector<int>> ans;
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    vector<int> temp;
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    vector<int> arr;
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    for (int i = 1; i <= n; i++) arr.push_back(i);
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    solve(arr, ans, temp, k, 0);
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    return ans;
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  }
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};