[Bit Manipulation] interview questions #6

[rygh4775]

Conversion: Write a function to determine the number of bits you would need to flip to convert integer A to integer B.

[btakeya]

to make A into B by flipping bits, flip different bits between A and B.

1. different bits between A and B: A ^ B (XOR)
2. count how many 1 bits in result of 1.

   # simple method: shift and count
   def count1s_1(num):
   count = 0
   while num > 0:
    if num % 2 == 1:
      count += 1
    num >>= 1
   return count
   # flip 1s
   def count1s_2(num):
   count = 0
   while num != 0:
    count += 1
    num &= (num - 1)
   return count