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 Approach:



Solution in C++:


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