CodeFights - Count Bits - Solution

Problem

Implement the missing code, denoted by ellipses. You may not modify the pre-existing code.

Implement a function that, given an integer n, uses a specific method on it and returns the number of bits in its binary representation.

Note: in this task and most of the following tasks you will be given a code snippet with some part of it replaced by the ellipsis (...). Only this part is allowed to be changed.

Example

For n = 50, the output should be
countBits(n) = 6.

5010 = 1100102, a number that consists of 6 digits. Thus, the output should be 6.

Input/Output

• [execution time limit] 4 seconds (py)
• [input] integer n
  A positive integer.
  Guaranteed constraints:
  1 ≤ n ≤ 109.
• [output] integer
  The number of bits in binary representation of n.

Solution

It is expected to only replace the ellipsis with the code that would give you the bit length of the given integer. 

def countBits(n):
     return n.bit_length()