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Add number/ntt_without_mll.cc 

Signed-off-by: subcrip <contact@subc.rip>
This commit is contained in:
subcrip 2024-11-21 02:53:38 +00:00
parent d7f3dafa12
commit f107381e58
1 changed files with 67 additions and 0 deletions
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number/ntt_without_mll.cc Normal file
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template <ll M>
ll qpow_m(ll b, ll p) {
if (b == 0 and p != 0) return 0;
if (p == 0) return 1;
ll half = qpow_m<M>(b, p / 2);
if (p % 2 == 1) return (half * half % M)* b % M;
else return half * half % M;
}
template <ll M>
void ntt(vector<ll>& y, bool idft) {
int n = y.size();
vector<int> rev(n);
for (int i = 0; i < n; ++i) {
rev[i] = rev[i >> 1] >> 1;
if (i & 1) {
rev[i] |= n >> 1;
}
}
for (int i = 0; i < n; ++i) {
if (i < rev[i]) {
swap(y[i], y[rev[i]]);
}
}
vector<ll> roots = { 0, 1 };
if (roots.size() < n) {
int k = lsp(roots.size());
roots.resize(n);
for (; (1 << k) < n; ++k) {
ll e = qpow_m<M>(31, 1 << lsp(M - 1) - k - 1);
for (int i = 1 << k - 1; i < (1 << k); ++i) {
roots[2 * i] = roots[i];
roots[2 * i + 1] = roots[i] * e % M;
}
}
}
for (int h = 2; h <= n; h <<= 1) {
for (int j = 0; j < n; j += h) {
for (int k = j; k < j + h / 2; ++k) {
ll u = y[k], t = roots[k - j + h / 2] * y[k + h / 2] % M;
y[k] = (u + t) % M;
y[k + h / 2] = mod(u - t, M);
}
}
}
if (idft) {
reverse(y.begin() + 1, y.end());
ll inv = inverse(n, M);
for (int i = 0; i < n; ++i) {
y[i] = y[i] * inv % M;
}
}
}
template <ll M>
vector<ll> multiply(const vector<ll>& a, const vector<ll>& b) {
vector<ll> A(a.begin(), a.end()), B(b.begin(), b.end());
int n = 1;
while (n < a.size() + b.size()) n <<= 1;
A.resize(n), B.resize(n);
ntt<M>(A, false), ntt<M>(B, false);
for (int i = 0; i < n; ++i) {
A[i] = A[i] * B[i] % M;
}
ntt<M>(A, true);
return A;
}