box-lin / miniblog

https://bboxlin.github.io/miniblog/

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Bit Manipulation #5

Open box-lin opened 1 year ago

box-lin commented 1 year ago

n & (n-1) = n with flip the least significant 1 to 0

n=1000 then n-1 = 0111, n & (n-1) = 0
n=1110 then n-1 = 1101, n & (n-1) = 1100

191. Number of 1 Bits

Keep flip the least significant 1 to 0 until n <= 0

class Solution:
def hammingWeight(self, n: int) -> int:
    ans = 0
    while n > 0:
        n &= (n-1)
        ans += 1
    return ans