Created
September 16, 2019 19:20
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NTT from cp-algorithms
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#include <bits/stdc++.h> | |
using namespace std; | |
const int mod = 7340033; | |
const int root = 5; | |
const int root_1 = 4404020; | |
const int root_pw = 1 << 20; | |
long long inverse(long long x, int mod) { | |
long long res = 1; | |
int e = mod - 2; | |
while (e) { | |
if (e & 1) | |
res = res * x % mod; | |
x = x * x % mod; | |
e >>= 1; | |
} | |
return res; | |
} | |
void fft(vector<int> & a, bool invert) { | |
int n = a.size(); | |
for (int i = 1, j = 0; i < n; i++) { | |
int bit = n >> 1; | |
for (; j & bit; bit >>= 1) | |
j ^= bit; | |
j ^= bit; | |
if (i < j) | |
swap(a[i], a[j]); | |
} | |
for (int len = 2; len <= n; len <<= 1) { | |
int wlen = invert ? root_1 : root; | |
for (int i = len; i < root_pw; i <<= 1) | |
wlen = (int)(1LL * wlen * wlen % mod); | |
for (int i = 0; i < n; i += len) { | |
int w = 1; | |
for (int j = 0; j < len / 2; j++) { | |
int u = a[i+j], v = (int)(1LL * a[i+j+len/2] * w % mod); | |
a[i+j] = u + v < mod ? u + v : u + v - mod; | |
a[i+j+len/2] = u - v >= 0 ? u - v : u - v + mod; | |
w = (int)(1LL * w * wlen % mod); | |
} | |
} | |
} | |
if (invert) { | |
int n_1 = inverse(n, mod); | |
assert(n_1 * n % mod == 1); | |
for (int & x : a) | |
x = (int)(1LL * x * n_1 % mod); | |
} | |
} | |
vector<int> multiply(vector<int> const& a, vector<int> const& b) { | |
vector<int> fa(a.begin(), a.end()), fb(b.begin(), b.end()); | |
int n = 1; | |
while (n < a.size() + b.size()) | |
n <<= 1; | |
fa.resize(n); | |
fb.resize(n); | |
fft(fa, false); | |
fft(fb, false); | |
for (int i = 0; i < n; i++) | |
fa[i] = (int)(1LL * fa[i] * fb[i] % mod); | |
fft(fa, true); | |
return fa; | |
} | |
int main() { | |
vector<int> v = {2, 1, 0, 0}; | |
vector<int> w = {2, 1, 2, 1}; | |
auto res = multiply(v, w); | |
for (auto x : res) | |
cout << x << endl; | |
} |
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