<p>Given an array <code>intervals</code> where <code>intervals[i] = [l<sub>i</sub>, r<sub>i</sub>]</code> represent the interval <code>[l<sub>i</sub>, r<sub>i</sub>)</code>, remove all intervals that are covered by another interval in the list.</p>

<p>The interval <code>[a, b)</code> is covered by the interval <code>[c, d)</code> if and only if <code>c &lt;= a</code> and <code>b &lt;= d</code>.</p>

<p>Return <em>the number of remaining intervals</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> intervals = [[1,4],[3,6],[2,8]]
<strong>Output:</strong> 2
<strong>Explanation:</strong> Interval [3,6] is covered by [2,8], therefore it is removed.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> intervals = [[1,4],[2,3]]
<strong>Output:</strong> 1
</pre>

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

<ul>
	<li><code>1 &lt;= intervals.length &lt;= 1000</code></li>
	<li><code>intervals[i].length == 2</code></li>
	<li><code>0 &lt;= l<sub>i</sub> &lt; r<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
	<li>All the given intervals are <strong>unique</strong>.</li>
</ul>

class Solution {
public:
    int removeCoveredIntervals(vector<vector<int>>& intervals) {
        vector<pair<int, int>> intervalPairs;

        for(auto interval: intervals) {
            intervalPairs.push_back({interval[0], interval[1]});
        }

        auto comp = [](const pair<int, int>& p1, const pair<int, int>& p2) {
            if(p1.first == p2.first) {
                return p2.second < p1.second;
            }
            return p1.first < p2.first;
        };

        sort(intervalPairs.begin(), intervalPairs.end(), comp);

        int count = 0;
        int l = -1;
        int r = -1;
        for(auto interval: intervalPairs) {
            int nl = interval.first;
            int nr = interval.second;
            if(nr <= r) {
                count++;
            } else {
                l = nl;
                r = nr;
            }
        }
        return intervals.size() - count;
    }
};
16100