Maximum Number of Events That Can Be Attended LeetCode solution in C++

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class Solution {
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 public:
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  int maxEvents(vector<vector<int>> &events) {
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    int res = 0;
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    int m = 0;
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    for (auto x : events) m = max(m, x[1]);
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    sort(events.begin(), events.end());
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    int j = 0;
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    priority_queue<int, vector<int>, greater<int>> pq;
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    for (int i = 1; i <= m; i++) {
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      while (!pq.empty() && pq.top() < i) // end day is less than the current day
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        pq.pop();
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      while (j < events.size() && events[j][0] == i) // put all events start at day i
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        pq.push(events[j++][1]);
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      if (!pq.empty()) // we can attend an event today
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      {
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        pq.pop(); // remove the event
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        res++;    // count that event
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      }
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    }
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    return res;
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  }
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};