I am unable to get which of my answers are wrong

#1

In the end I just got 13/15 are correct but which ones are wrong and which ones are right that I don’t know but want to know about it. Also I have doubt in 4th and 6th question of it.

#2

can you share the questions?
i don’t have questions

#3

Which one line function can be used to get index of the least significant bit that is on (first 1 from right to left in binary representation of an integer) ?

log2( N ^ -N ) + 1

log2( N | -N ) + 1

log2( N & -N ) + 1

log2( N ~ -N ) + 1

#4

bitmask count set bits 2

Total number of factors of n

Total number of divisors of n

Total number of unset bits in binary representation of a n

Total number of set bits in binary representation of a n

#5

Explanation
One can use the property of 2s-complement here.
Fastest way to find 2s-complement of a number is to get the rightmost set bit and flip everything to the left of it.
eg: consider a 4 bit system
4=0100
2s complement of 4 = 1100, which nothing but -4
4&(-4)=0100.
Notice that there is only one set bit and its at rightmost set bit of 4
Similarly we can generalise this for n.
n&(-n) will contain only one set bit which is actually at the rightmost set bit position of n.
since there is only one set bit in n&(-n) , it is a power of 2.
So finally we can get the bit position by:

log2(n&(-n))+1

#6

where is question???

#7

Why +1 in the end and log2 in the starting?

#8

because without +1 we get index based on “zero based indexing”
but if we consider 1th bit not 0th bit then we have to add 1

#9 
bool get (int n)
{
    int x = 0;
    while( n )
    {
        x += n&1;
        n = n>>1;
    }
    return x;
}

Above function will return :-

Total number of divisors of n

Total number of factors of n

Total number of unset bits in binary representation of a n

Total number of set bits in binary representation of a n

This was 5th question and according to me the ans of this is option d. I have doubt in the question I posted above which is an extension of this one.

#10

got your point. thanks!

#11

this will be the answer

extract last bit and add it to x

now remove last bit

so at the end x will contain sum of all set bits
which is nothing but Total number of set bits in binary representation of a n

#12

@sakshi_singhal kindly give your feedback
it hardly takes a min

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#13

What about this? I have query in this question and not in the question you answered.

#14

which question? you can still ask
don’t worry

#15

Is it possible to discuss it over a call?

#16

i hope your doubt is resolved
so kindly give feedback