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2054. Two Best Non-Overlapping Events 👍

  • Time: $O(\texttt{sort})$
  • Space: $O(n)$
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struct Event {
  int time;
  int value;
  bool isStart;
};

class Solution {
 public:
  int maxTwoEvents(vector<vector<int>>& events) {
    int ans = 0;
    int maxValue = 0;
    vector<Event> evts;

    for (const vector<int>& event : events) {
      const int start = event[0];
      const int end = event[1];
      const int value = event[2];
      evts.emplace_back(start, value, true);
      evts.emplace_back(end + 1, value, false);
    }

    ranges::sort(evts, [](const Event& a, const Event& b) {
      return a.time == b.time ? a.isStart < b.isStart : a.time < b.time;
    });

    for (const auto& [_, value, isStart] : evts)
      if (isStart)
        ans = max(ans, value + maxValue);
      else
        maxValue = max(maxValue, value);

    return ans;
  }
};

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class Event {
  public int time;
  public int value;
  public int isStart;
  public Event(int time, int value, int isStart) {
    this.time = time;
    this.value = value;
    this.isStart = isStart;
  }
}

class Solution {
  public int maxTwoEvents(int[][] events) {
    int ans = 0;
    int maxValue = 0;
    Event[] evts = new Event[events.length * 2];

    for (int i = 0; i < events.length; ++i) {
      final int start = events[i][0];
      final int end = events[i][1];
      final int value = events[i][2];
      evts[i * 2] = new Event(start, value, 1);
      evts[i * 2 + 1] = new Event(end + 1, value, 0);
    }

    Arrays.sort(evts,
                (a, b)
                    -> a.time == b.time ? Integer.compare(a.isStart, b.isStart)
                                        : Integer.compare(a.time, b.time));

    for (Event evt : evts)
      if (evt.isStart == 1)
        ans = Math.max(ans, evt.value + maxValue);
      else
        maxValue = Math.max(maxValue, evt.value);

    return ans;
  }
}

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class Solution:
  def maxTwoEvents(self, events: list[list[int]]) -> int:
    ans = 0
    maxValue = 0
    evts = []  # (time, isStart, value)

    for s, e, v in events:
      evts.append((s, 1, v))
      evts.append((e + 1, 0, v))

    # When two events have the same time, the one is not start will be in the front
    evts.sort()

    for _, isStart, value in evts:
      if isStart:
        ans = max(ans, value + maxValue)
      else:
        maxValue = max(maxValue, value)

    return ans