# LeetCode 1356. Sort Integers by The Number of 1 Bits

## Question

Given an integer array `arr`

. You have to sort the integers in the array in ascending order by the number of **1’s** in their binary representation and in case of two or more integers have the same number of **1’s** you have to sort them in ascending order.

Return *the sorted array*.

**Example**

1 | Input: arr = [0,1,2,3,4,5,6,7,8] |

## Solution

It’s a customized sorting problem. But we need to convert `int`

to `Integer`

, so that we can sort them.

## Code

1 | // time: O(nlogn), space: O(n) |