Question

How to count the total set bits in all numbers from 1 to N in C

Answer 1

#include <stdio.h> 
  
unsigned int count_set_bits(unsigned int n) { 
    unsigned int count = 0; 
    while (n) { 
        count += n & 1; 
        n >>= 1; 
    } 
    return count; 
}  

unsigned int count_total_set_bits(unsigned int n) { 
    int setBitCount = 0; 
  
    for (int i = 1; i <= n; i++) 
        setBitCount += count_set_bits(i); 
  
    return setBitCount; 
} 

int main() 
{ 
    int n = 6; 
    /*
        0001
        0010
        0011
        0100
        0101
        0110
    */
    
    printf("%i", count_total_set_bits(n)); 
    
    return 0; 
} 



/*
run:

9

*/

 

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