cp_library/bit/ctz64_fn.py

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• Last update: 2025-03-30 20:17:47+09:00

Depends on

• cp_library/bit/popcnt64_fn.py

Code

import cp_library.bit.__header__
from cp_library.bit.popcnt64_fn import popcnt64

def ctz64(x): return popcnt64(~x & (x - 1))

'''
╺━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╸
             https://kobejean.github.io/cp-library               
'''

def popcnt64(x):
    x = ((x >> 1)  & 0x5555555555555555) + (x & 0x5555555555555555)
    x = ((x >> 2)  & 0x3333333333333333) + (x & 0x3333333333333333)
    x = ((x >> 4)  & 0x0f0f0f0f0f0f0f0f) + (x & 0x0f0f0f0f0f0f0f0f)
    x = ((x >> 8)  & 0x00ff00ff00ff00ff) + (x & 0x00ff00ff00ff00ff)
    x = ((x >> 16) & 0x0000ffff0000ffff) + (x & 0x0000ffff0000ffff)
    x = ((x >> 32) & 0x00000000ffffffff) + (x & 0x00000000ffffffff)
    return x

def ctz64(x): return popcnt64(~x & (x - 1))

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