competitive-programming-library
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View the Project on GitHub yu-0811/competitive-programming-library
algorithm_library/python/math/FFT.py
- View this file on GitHub
- Last update: 2025-06-28 16:39:56+09:00
- Link: https://github.com/atcoder/ac-library/blob/master/document_ja/convolution.md
- Link: https://github.com/shakayami/ACL-for-python/blob/master/convolution.py
Code
"""
shakayami 製 ACL をそのまま窃盗
https://github.com/shakayami/ACL-for-python/blob/master/convolution.py
本家ACLドキュメント : https://github.com/atcoder/ac-library/blob/master/document_ja/convolution.md
"""
class FFT():
def primitive_root_constexpr(self,m):
if m==2:return 1
if m==167772161:return 3
if m==469762049:return 3
if m==754974721:return 11
if m==998244353:return 3
divs=[0]*20
divs[0]=2
cnt=1
x=(m-1)//2
while(x%2==0):x//=2
i=3
while(i*i<=x):
if (x%i==0):
divs[cnt]=i
cnt+=1
while(x%i==0):
x//=i
i+=2
if x>1:
divs[cnt]=x
cnt+=1
g=2
while(1):
ok=True
for i in range(cnt):
if pow(g,(m-1)//divs[i],m)==1:
ok=False
break
if ok:
return g
g+=1
def bsf(self,x):
res=0
while(x%2==0):
res+=1
x//=2
return res
rank2=0
root=[]
iroot=[]
rate2=[]
irate2=[]
rate3=[]
irate3=[]
def __init__(self,MOD):
self.mod=MOD
self.g=self.primitive_root_constexpr(self.mod)
self.rank2=self.bsf(self.mod-1)
self.root=[0 for i in range(self.rank2+1)]
self.iroot=[0 for i in range(self.rank2+1)]
self.rate2=[0 for i in range(self.rank2)]
self.irate2=[0 for i in range(self.rank2)]
self.rate3=[0 for i in range(self.rank2-1)]
self.irate3=[0 for i in range(self.rank2-1)]
self.root[self.rank2]=pow(self.g,(self.mod-1)>>self.rank2,self.mod)
self.iroot[self.rank2]=pow(self.root[self.rank2],self.mod-2,self.mod)
for i in range(self.rank2-1,-1,-1):
self.root[i]=(self.root[i+1]**2)%self.mod
self.iroot[i]=(self.iroot[i+1]**2)%self.mod
prod=1;iprod=1
for i in range(self.rank2-1):
self.rate2[i]=(self.root[i+2]*prod)%self.mod
self.irate2[i]=(self.iroot[i+2]*iprod)%self.mod
prod=(prod*self.iroot[i+2])%self.mod
iprod=(iprod*self.root[i+2])%self.mod
prod=1;iprod=1
for i in range(self.rank2-2):
self.rate3[i]=(self.root[i+3]*prod)%self.mod
self.irate3[i]=(self.iroot[i+3]*iprod)%self.mod
prod=(prod*self.iroot[i+3])%self.mod
iprod=(iprod*self.root[i+3])%self.mod
def butterfly(self,a):
n=len(a)
h=(n-1).bit_length()
LEN=0
while(LEN<h):
if (h-LEN==1):
p=1<<(h-LEN-1)
rot=1
for s in range(1<<LEN):
offset=s<<(h-LEN)
for i in range(p):
l=a[i+offset]
r=a[i+offset+p]*rot
a[i+offset]=(l+r)%self.mod
a[i+offset+p]=(l-r)%self.mod
rot*=self.rate2[(~s & -~s).bit_length()-1]
rot%=self.mod
LEN+=1
else:
p=1<<(h-LEN-2)
rot=1
imag=self.root[2]
for s in range(1<<LEN):
rot2=(rot*rot)%self.mod
rot3=(rot2*rot)%self.mod
offset=s<<(h-LEN)
for i in range(p):
a0=a[i+offset]
a1=a[i+offset+p]*rot
a2=a[i+offset+2*p]*rot2
a3=a[i+offset+3*p]*rot3
a1na3imag=(a1-a3)%self.mod*imag
a[i+offset]=(a0+a2+a1+a3)%self.mod
a[i+offset+p]=(a0+a2-a1-a3)%self.mod
a[i+offset+2*p]=(a0-a2+a1na3imag)%self.mod
a[i+offset+3*p]=(a0-a2-a1na3imag)%self.mod
rot*=self.rate3[(~s & -~s).bit_length()-1]
rot%=self.mod
LEN+=2
def butterfly_inv(self,a):
n=len(a)
h=(n-1).bit_length()
LEN=h
while(LEN):
if (LEN==1):
p=1<<(h-LEN)
irot=1
for s in range(1<<(LEN-1)):
offset=s<<(h-LEN+1)
for i in range(p):
l=a[i+offset]
r=a[i+offset+p]
a[i+offset]=(l+r)%self.mod
a[i+offset+p]=(l-r)*irot%self.mod
irot*=self.irate2[(~s & -~s).bit_length()-1]
irot%=self.mod
LEN-=1
else:
p=1<<(h-LEN)
irot=1
iimag=self.iroot[2]
for s in range(1<<(LEN-2)):
irot2=(irot*irot)%self.mod
irot3=(irot*irot2)%self.mod
offset=s<<(h-LEN+2)
for i in range(p):
a0=a[i+offset]
a1=a[i+offset+p]
a2=a[i+offset+2*p]
a3=a[i+offset+3*p]
a2na3iimag=(a2-a3)*iimag%self.mod
a[i+offset]=(a0+a1+a2+a3)%self.mod
a[i+offset+p]=(a0-a1+a2na3iimag)*irot%self.mod
a[i+offset+2*p]=(a0+a1-a2-a3)*irot2%self.mod
a[i+offset+3*p]=(a0-a1-a2na3iimag)*irot3%self.mod
irot*=self.irate3[(~s & -~s).bit_length()-1]
irot%=self.mod
LEN-=2
def convolution(self, a : list[int], b : list[int]) -> list[int]:
"""
res[i] = Σ_{j=0}^{i} a[j]b[i-j] (0-indexed)
わかりやすくいうと、インデックスの和が i になるような a, b の積の総和
ex. a = [1, 2, 3], b = [4, 5, 6]
res = [1*4, 1*5 + 2*4, 1*6 + 2*5 + 3*4, 2*6 + 3*5, 3*6]
= [4, 13, 28, 27, 18]
(インデックスでいうと、res[0] = a[0]*b[0], res[1] = a[0]*b[1] + a[1]*b[0], ...)
時間計算量
L = |a| + |b| として、O(L log L + log mod)
"""
n=len(a);m=len(b)
if not(a) or not(b):
return []
if min(n,m)<=40:
res=[0]*(n+m-1)
for i in range(n):
for j in range(m):
res[i+j]+=a[i]*b[j]
res[i+j]%=self.mod
return res
z=1<<((n+m-2).bit_length())
a=a+[0]*(z-n)
b=b+[0]*(z-m)
self.butterfly(a)
self.butterfly(b)
c=[(a[i]*b[i])%self.mod for i in range(z)]
self.butterfly_inv(c)
iz=pow(z,self.mod-2,self.mod)
for i in range(n+m-1):
c[i]=(c[i]*iz)%self.mod
return c[:n+m-1]Traceback (most recent call last):
File "/opt/hostedtoolcache/Python/3.11.0/x64/lib/python3.11/site-packages/onlinejudge_verify/documentation/build.py", line 71, in _render_source_code_stat
bundled_code = language.bundle(stat.path, basedir=basedir, options={'include_paths': [basedir]}).decode()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/opt/hostedtoolcache/Python/3.11.0/x64/lib/python3.11/site-packages/onlinejudge_verify/languages/python.py", line 96, in bundle
raise NotImplementedError
NotImplementedError