<p>You are given a 2D array of integers <code>envelopes</code> where <code>envelopes[i] = [w<sub>i</sub>, h<sub>i</sub>]</code> represents the width and the height of an envelope.</p>

<p>One envelope can fit into another if and only if both the width and height of one envelope are greater than the other envelope&#39;s width and height.</p>

<p>Return <em>the maximum number of envelopes you can Russian doll (i.e., put one inside the other)</em>.</p>

<p><strong>Note:</strong> You cannot rotate an envelope.</p>

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

<pre>
<strong>Input:</strong> envelopes = [[5,4],[6,4],[6,7],[2,3]]
<strong>Output:</strong> 3
<strong>Explanation:</strong> The maximum number of envelopes you can Russian doll is <code>3</code> ([2,3] =&gt; [5,4] =&gt; [6,7]).
</pre>

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

<pre>
<strong>Input:</strong> envelopes = [[1,1],[1,1],[1,1]]
<strong>Output:</strong> 1
</pre>

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

<ul>
	<li><code>1 &lt;= envelopes.length &lt;= 10<sup>5</sup></code></li>
	<li><code>envelopes[i].length == 2</code></li>
	<li><code>1 &lt;= w<sub>i</sub>, h<sub>i</sub> &lt;= 10<sup>5</sup></code></li>
</ul>

class Solution {
public:

int lis(vector<int> arr){
    vector<int> ans;
    for(int i=0;i<arr.size();i++){
        if(ans.size()==0||ans[ans.size()-1]<arr[i]) ans.push_back(arr[i]);
        else{
            auto id=lower_bound(ans.begin(),ans.end(),arr[i])-ans.begin();
            ans[id]=arr[i];
        }
    }
    return ans.size();
}
static bool comp(const vector<int>& a, const vector<int>& b) {
    if (a[0] == b[0]) return a[1] > b[1];
    return a[0] < b[0];
}
    int maxEnvelopes(vector<vector<int>>& grid) {
        
        sort(grid.begin(),grid.end(),comp);

        vector<int> arr;
        for(auto it:grid) arr.push_back(it[1]);

        return lis(arr);


    }
};
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