Increasing Subsequences LeetCode solution in C++

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class Solution {
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 public:
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  set<vector<int>> ans;
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  void solve(int start, int n, vector<int> &nums, vector<int> &result) {
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    if (result.size() > 1) ans.insert(result);
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    if (start == n) {
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      return;
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    }
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    for (int i = start; i < n; i++) {
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      if (result.empty() || result.back() <= nums[i]) {
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        result.push_back(nums[i]);
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        solve(i + 1, n, nums, result);
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        result.pop_back();
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      }
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    }
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  }
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  vector<vector<int>> findSubsequences(vector<int> &nums) {
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    int n = nums.size();
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    vector<int> result;
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    solve(0, n, nums, result);
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    return vector<vector<int>>(ans.begin(), ans.end());
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  }
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};