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Problem Definition:

Write a one line C function to return position of first 1 from right to left, in binary representation of an Integer.

Solution:

Example 18(010010)

1. Take two's complement(i.e. -n) of the given no as all bits are revertedexcept the first '1' from right to left (10111)2  Do an bit-wise & with original no, this will return no with therequired one only (00010)3  Take the log2 of the no, you will get position -1 (1)4  Add 1 (2)

Code:

unsigned int getFirstSetBitPos(int n){   return log2(n&-n)+1;//or log2(n & (n^(n-1)))+1}

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