提交记录 16764


用户 题目 状态 得分 用时 内存 语言 代码长度
Saisyc 1002. 测测你的多项式乘法 Accepted 100 258.741 ms 32400 KB C++ 1.24 KB
提交时间 评测时间
2021-10-18 01:02:28 2021-10-18 01:02:30
#include <algorithm>

const int N =     1 << 21;
const int p =    81 << 21 | 1;
const int g =  1167 << 12 | 1;
const int h = 11443 << 12 | 1;

inline int pow_modp(int a, int b) { int x = 1; for(; b; a = (long long)a * a % p, b >>= 1) if(b & 1) x = (long long)x * a % p; return x; }

int ntt_sup[N];
inline void ntt(auto a[], int n, const int g) {
	auto b = ntt_sup, j = a, _j = a; int _n = n >> 1, i, k, _k, w, _w;
	for(i = 1, w = pow_modp(g, (p - 1) / n); i < n; i <<= 1, w = (long long)w * w % p, std :: swap(a, b))
		for(k = 0, j = a, _j = a + _n, _w = 1; k != n; k += i, _w = (long long)_w * w % p)
			for(_k = k, k += i; _k != k; ++j, ++_j, ++_k)
				b[_k] = *j + *_j < p ? *j + *_j : *j + *_j - p,
				b[_k + i] = (long long)(*j - *_j + p) * _w % p;
	if(b != ntt_sup) std :: copy(a, a + n, b);
}

int a[N], b[N];
void poly_multiply(unsigned *aa, int n, unsigned *bb, int m, unsigned *c) {
	std :: copy(aa, aa + n + 1, a), std :: copy(bb, bb + m + 1, b);
	m += n; for(n = 1; n <= m; n <<= 1); ++m;
	ntt(a, n, g), ntt(b, n, g);     for(int i = 0; i < n; ++i) a[i] = (long long)a[i] * b[i] % p; ntt(a, n, h);
	int inv_n = pow_modp(n, p - 2); for(int i = 0; i < m; ++i) a[i] = (long long)a[i] * inv_n % p;
	for(int i = 0; i < m; ++i) c[i] = a[i] < 0 ? a[i] + p : a[i];
}

CompilationN/AN/ACompile OKScore: N/A

Testcase #1258.741 ms31 MB + 656 KBAcceptedScore: 100


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