leetcode-problemset/leetcode/problem/pascals-triangle-ii.html

<p>Given an integer <code>rowIndex</code>, return the <code>rowIndex<sup>th</sup></code> (<strong>0-indexed</strong>) row of the <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> rowIndex = 3
<strong>Output:</strong> [1,3,3,1]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> rowIndex = 0
<strong>Output:</strong> [1]
</pre><p><strong class="example">Example 3:</strong></p>
<pre><strong>Input:</strong> rowIndex = 1
<strong>Output:</strong> [1,1]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>0 &lt;= rowIndex &lt;= 33</code></li>
</ul>

<p>&nbsp;</p>
<p><strong>Follow up:</strong> Could you optimize your algorithm to use only <code>O(rowIndex)</code> extra space?</p>