<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>>& v) {
        int n=v.size();
        map<int,int>mp;
        vector<vector<int>>rem;
        for(auto &i:v){
            int x=i[0],y=i[1];
            mp[x]=max(mp[x],y);
        }
        for(auto &i:mp)rem.push_back({i.first,i.second});
        mp.clear();
        for(auto &i:rem){
            int x=i[0],y=i[1];
            auto itr=mp.lower_bound(y);
            if(itr!=mp.end()&&(*itr).second<x)continue;
            if(mp.find(y)==mp.end())mp[y]=x;
            else mp[y]=min(mp[y],x);
        }
        int ans=n;
        for(auto &i:v){
            int x=i[0],y=i[1];
            auto itr=mp.lower_bound(y);
            if((*itr).first==y&&(*itr).second==x)continue;
            else ans--;
        }
        return ans;
    }
};
18300