# 0119. Pascal's Triangle II

<https://leetcode.com/problems/pascals-triangle-ii>

## Description

Given an integer `rowIndex`, return the `rowIndexth` (**0-indexed**) row of the **Pascal's triangle**.

In **Pascal's triangle**, each number is the sum of the two numbers directly above it as shown:

![](https://upload.wikimedia.org/wikipedia/commons/0/0d/PascalTriangleAnimated2.gif) **Example 1:**

```
**Input:** rowIndex = 3
**Output:** [1,3,3,1]
```

**Example 2:**

```
**Input:** rowIndex = 0
**Output:** [1]
```

**Example 3:**

```
**Input:** rowIndex = 1
**Output:** [1,1]
```

**Constraints:**

* `0 <= rowIndex <= 33`

**Follow up:** Could you optimize your algorithm to use only `O(rowIndex)` extra space?

## ac

```java
```