<p>You are given a <strong>0-indexed</strong> 2D integer array <code>flowers</code>, where <code>flowers[i] = [start<sub>i</sub>, end<sub>i</sub>]</code> means the <code>i<sup>th</sup></code> flower will be in <strong>full bloom</strong> from <code>start<sub>i</sub></code> to <code>end<sub>i</sub></code> (<strong>inclusive</strong>). You are also given a <strong>0-indexed</strong> integer array <code>people</code> of size <code>n</code>, where <code>people[i]</code> is the time that the <code>i<sup>th</sup></code> person will arrive to see the flowers.</p>

<p>Return <em>an integer array </em><code>answer</code><em> of size </em><code>n</code><em>, where </em><code>answer[i]</code><em> is the <strong>number</strong> of flowers that are in full bloom when the </em><code>i<sup>th</sup></code><em> person arrives.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/03/02/ex1new.jpg" style="width: 550px; height: 216px;" />
<pre>
<strong>Input:</strong> flowers = [[1,6],[3,7],[9,12],[4,13]], people = [2,3,7,11]
<strong>Output:</strong> [1,2,2,2]
<strong>Explanation: </strong>The figure above shows the times when the flowers are in full bloom and when the people arrive.
For each person, we return the number of flowers in full bloom during their arrival.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/03/02/ex2new.jpg" style="width: 450px; height: 195px;" />
<pre>
<strong>Input:</strong> flowers = [[1,10],[3,3]], people = [3,3,2]
<strong>Output:</strong> [2,2,1]
<strong>Explanation:</strong> The figure above shows the times when the flowers are in full bloom and when the people arrive.
For each person, we return the number of flowers in full bloom during their arrival.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= flowers.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>flowers[i].length == 2</code></li>
	<li><code>1 &lt;= start<sub>i</sub> &lt;= end<sub>i</sub> &lt;= 10<sup>9</sup></code></li>
	<li><code>1 &lt;= people.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>1 &lt;= people[i] &lt;= 10<sup>9</sup></code></li>
</ul>

enum EventType {
    // Cases are numbered in that order in which they have to be sorted.
    BLOOM_STARTS = 0,
    PERSON_ARRIVES = 1,
    BLOOM_ENDS = 2,
};

struct Event {
    int time;
    EventType type;
    int personIndex;
    
    Event(int time, EventType type) : time(time), type(type), personIndex(-1) {}
    Event(int time, EventType type, int personIndex) : time(time), type(type), personIndex(personIndex) {}
};

class Solution {
public:
    vector<int> fullBloomFlowers(vector<vector<int>>& flowers, vector<int>& people) {
        vector<Event> events;
        events.reserve(flowers.size() * 2 + people.size());
        for (const auto& bloom: flowers) {
            events.push_back(Event(bloom[0], BLOOM_STARTS));
            events.push_back(Event(bloom[1], BLOOM_ENDS));
        }
        for (int i = 0; i < people.size();i ++) {
            events.push_back(Event(people[i], PERSON_ARRIVES, i));
        }
        
        sort(events.begin(), events.end(), [](const Event& left, const Event& right) {
            if (left.time != right.time) {
                return left.time < right.time;
            } 
            return left.type < right.type;
        });
        
        vector<int> result(people.size());
        int nowBlooming = 0;
        for (const Event& event: events) {
            switch (event.type) {
                case BLOOM_STARTS:
                    nowBlooming ++;
                    break;
                case BLOOM_ENDS:
                    nowBlooming --;
                    break;
                case PERSON_ARRIVES:
                    result[event.personIndex] = nowBlooming;
                    break;
                default:
                    throw;
            }
        }
        return result;
    }
};
88301