4 Lines Python AC Solution Beats 100%

  • 0

    It's fast because using bit-manipulation. Algorithm is O(logn), because each input n has number of logn binary digits.

    In the while loop:
    n shift 1 position right until become zero
    if 2^0 == 1: count +1

    class Solution(object):
        def hammingWeight(self, n):
            if n < 0: return bin(n).count('1')        # correction according to Jun_Tang
            count = 0
            while n > 0:
                count, n = count+(n&1), n>>1
            return count

  • 0

    i wonder if this solution would for negative numbers.

  • 0

    @Jun_Tang Thanks for your correction! Codes are updated, but sadly, the performance dropped from 39ms to 45ms. Wondering that why there's no negative numbers in test cases.

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