<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:
    memo = {}

    def getRow(self, rowNum):            
        if rowNum in self.memo:
            return self.memo[rowNum]

        rows = [0 for _ in range(rowNum)]
        rows[0] = 1
        rows[-1] = 1

        for i in range(1, len(rows) - 1):
            prev_row = self.getRow(rowNum - 1)
            rows[i] = prev_row[i - 1] + prev_row[i]

        self.memo[rowNum] = rows

        return rows

    def generate(self, numRows: int) -> List[List[int]]:
        self.getRow(numRows)
        
        output = [[1]]

        for i in range(2, numRows + 1):
            output.append(self.memo[i])

        return output
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