Closest Room LeetCode solution in C++

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class Solution {
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 public:
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  vector<int> closestRoom(vector<vector<int>> &rooms, vector<vector<int>> &queries) {
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    const int n = rooms.size(), m = queries.size();
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    for (int i = 0; i < m; i++) queries[i].push_back(i);
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    sort(begin(queries), end(queries), [](const auto &a, const auto &b) { return a[1] > b[1]; });
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    sort(begin(rooms), end(rooms), [](const auto &a, const auto &b) { return a[1] > b[1]; });
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    vector<int> ans(m, -1);
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    set<int> ids;
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    int j = 0;
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    for (const auto &q : queries) {
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      while (j < n && rooms[j][1] >= q[1]) ids.insert(rooms[j++][0]);
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      if (ids.empty()) continue;
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      int id = q[0];
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      auto it = ids.lower_bound(id);
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      int id1 = (it != end(ids)) ? *it : INT_MAX;
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      int id2 = id1;
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      if (it != begin(ids)) id2 = *prev(it);
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      ans[q[2]] = abs(id1 - id) < abs(id2 - id) ? id1 : id2;
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    }
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    return ans;
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  }
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};