cp_library/bit/ctz32_fn.py

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

Depends on

• cp_library/bit/popcnt32_fn.py

Required by

• cp_library/alg/graph/bit_graph_cls.py
• cp_library/bit/clz32_fn.py

Verified with

• test/library-checker/graph/chromatic_number.test.py

Code

import cp_library.bit.__header__
from cp_library.bit.popcnt32_fn import popcnt32

def ctz32(x): return popcnt32(~x & (x - 1))

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

def popcnt32(x):
    x = ((x >> 1)  & 0x55555555) + (x & 0x55555555)
    x = ((x >> 2)  & 0x33333333) + (x & 0x33333333)
    x = ((x >> 4)  & 0x0f0f0f0f) + (x & 0x0f0f0f0f)
    x = ((x >> 8)  & 0x00ff00ff) + (x & 0x00ff00ff)
    x = ((x >> 16) & 0x0000ffff) + (x & 0x0000ffff)
    return x

def ctz32(x): return popcnt32(~x & (x - 1))

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