Count Set Bits

Problem

Count the number of 1 bits in the binary representation of a non-negative integer n.

Use Brian Kernighan's trick, which clears the lowest set bit with the expression n = n & (n - 1), looping exactly popcount times. Return the count as an integer.

Hint

n & (n - 1) removes the lowest set bit, so count how many times you can do it.

Test cases

case 1

in: [0]

expected: 0

case 2

in: [7]

expected: 3

case 3

in: [8]

expected: 1

case 4

in: [255]

expected: 8

case 5

in: [1024]

expected: 1

Starter codePython

def count_set_bits(n):
    # Your code here
    pass

5 test cases · run your code against them in the editor