top of page

### Looking to master object-oriented and system design for tech interviews or career growth?

• Improve your system design and machine coding skills.

• Study with our helpful resources.

• Prepare for technical interviews and advance your career.

**We're in beta mode and would love to hear your feedback.

Search

# Count Total Set Bits - InterviewBit Solution

Problem: Count Total Set Bits

### Problem Description:

Given a positive integer A, the task is to count the total number of set bits in the binary representation of all the numbers from 1 to A Return the count modulo 109 + 7.

Problem Constraints

`1 <= A <= 109`

Input Format

The first and only argument is an integer A.

Output Format

Return an integer denoting the ( Total number of set bits in the binary representation of all the numbers from 1 to A )modulo 109 + 7.

Example Input

```Input 1:
A = 3
Input 2:
A = 1 ```

Example Output

```Output 1:
4
Output 2:
1 ```

### Example Explanation

Explanation 1:

``` DECIMAL    BINARY  SET BIT COUNT
1          01        1
2          10        1
3          11        2
1 + 1 + 2 = 4
Answer = 4 % 1000000007 = 4

```

Explanation 2:

``` A = 1
DECIMAL    BINARY  SET BIT COUNT
1          01        1
Answer = 1 % 1000000007 = 1```

### Solution in C++:

If you have any questions or queries, feel free to drop a comment in the comments section below.

### Note: Help us improve this blog

If you have a better solution, and you think you can help your peers to understand this problem better, then please drop your solution and approach in the comments section below.

We will upload your approach and solution here by giving you the proper credit so that you can showcase it among your peers.

bottom of page