```
public class Solution
extends Object
```
338 - Counting Bits\. Easy Given an integer `n`, return _an array_ `ans` _of length_ `n + 1` _such that for each_ `i` (`0 <= i <= n`)_,_ `ans[i]` _is the **number of**_ `1`_**'s** in the binary representation of_ `i`. **Example 1:** **Input:** n = 2 **Output:** [0,1,1] **Explanation:** 0 --> 0 1 --> 1 2 --> 10 **Example 2:** **Input:** n = 5 **Output:** [0,1,1,2,1,2] **Explanation:** 0 --> 0 1 --> 1 2 --> 10 3 --> 11 4 --> 100 5 --> 101 **Constraints:** * 0 <= n <= 10⁵ **Follow up:** * It is very easy to come up with a solution with a runtime of `O(n log n)`. Can you do it in linear time `O(n)` and possibly in a single pass? * Can you do it without using any built-in function (i.e., like `__builtin_popcount` in C++)?

Class Solution