<p>Given an integer <code>numRows</code>, return the first numRows of <strong>Pascal&#39;s triangle</strong>.</p>

<p>In <strong>Pascal&#39;s triangle</strong>, each number is the sum of the two numbers directly above it as shown:</p>
<img alt="" src="https://upload.wikimedia.org/wikipedia/commons/0/0d/PascalTriangleAnimated2.gif" style="height:240px; width:260px" />
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> numRows = 5
<strong>Output:</strong> [[1],[1,1],[1,2,1],[1,3,3,1],[1,4,6,4,1]]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> numRows = 1
<strong>Output:</strong> [[1]]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= numRows &lt;= 30</code></li>
</ul>

class Solution{
private:
    void helper(int row, vector<int>& curr){
    curr.push_back(1);
    int res=1;
    for(int i=1; i<row; i++){
    res*=(row-i);
    res=res/i;
    curr.push_back(res);
    }
    }

public:
    vector<vector<int>> generate(int N){
    vector<vector<int>> res;
    for(int i=1; i<=N; i++){
    vector<int> curr;
    helper(i,curr);
    res.push_back(curr);
    }
    return res;
    }
};  
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