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  • 多项式板子·新

    upd于2.19:拉格朗日反演、多项式倍增快速幂

    (好像是还差一个多项式取模...)算了不写了

    注意本板子使用过程中:每个函数传的len一定要保证是2的倍数,并且传递的数组需要保证他有多于2*len的空间

    每个函数传进来的指针保证[0,len)有值,[len,2*len)有定义

    注意new出来的内存一定要清零,不然肯定会炸

    #include <cstdio>
    #include <algorithm>
    using namespace std;
    
    const int p = 998244353;
    
    int qpow(int x, int y)
    {
    	int res = 1;
    	while (y > 0)
    	{
    		if (y & 1) res = res * (long long)x % p;
    		x = x * (long long)x % p, y >>= 1;
    	}
    	return res;
    }
    
    void ntt(int *a, int len, int flag)
    {
    	int *r = new int[len];
    	r[0] = 0;
    	for (int i = 1; i < len; i++) r[i] = (r[i >> 1] >> 1) | ((i & 1) * (len >> 1));
    	for (int i = 0; i < len; i++) if (i < r[i]) swap(a[i], a[r[i]]);
    	for (int i = 1; i < len; i <<= 1)
    	{
    		int g1 = qpow(3, (p - 1) / (i * 2));
    		for (int j = 0; j < len; j += i << 1)
    			for (int g = 1, k = 0; k < i; k++, g = g * (long long)g1 % p)
    			{
    				int t = a[j + i + k] * (long long)g % p;
    				a[j + i + k] = ((a[j + k] - t) % p + p) % p;
    				a[j + k] = (a[j + k] + t) % p;
    			}
    	}
    	if (flag == -1)
    	{
    		reverse(a + 1, a + len);
    		for (int i = 0, inv = qpow(len, p - 2); i < len; i++) a[i] = a[i] * (long long)inv % p;
    	}
    	delete []r;
    }
    
    void poly_inv(int *a, int len)
    {
    	if (len == 1) { a[0] = qpow(a[0], p - 2); return; }
    	int len1 = len / 2;
    	int *f0 = new int[len * 2];
    	for (int i = 0; i < len1; i++) f0[i] = a[i];
    	for (int i = len1; i < len * 2; i++) f0[i] = 0;
    	poly_inv(f0, len1);
    	for (int i = len1; i < len * 2; i++) f0[i] = 0;
    	ntt(f0, len * 2, 1), ntt(a, len * 2, 1);
    	for (int i = 0; i < len * 2; i++) a[i] = ((2 * f0[i] % p - a[i] * (long long)f0[i] % p * f0[i] % p) % p + p) % p;
    	ntt(a, len * 2, -1);
    	for (int i = len; i < len * 2; i++) a[i] = 0;
    	delete []f0;
    }
    
    void poly_derivation(int *a, int len)
    {
    	for (int i = 1; i < len; i++)
    		a[i - 1] = a[i] * (long long)i % p;
    	a[len - 1] = 0;
    }
    
    void poly_intergal(int *a, int len)
    {
    	for (int i = len + 1; i >= 1; i--)
    		a[i] = a[i - 1] * (long long)qpow(i, p - 2) % p;
    	a[0] = 0;
    }
    
    void poly_ln(int *a, int len)
    {
    	int *b = new int[len * 2];
    	for (int i = 0; i < len; i++) b[i] = a[i];
    	for (int i = len; i < len * 2; i++) b[i] = 0;
    	poly_derivation(b, len);
    	poly_inv(a, len);
    	ntt(a, len * 2, 1);
    	ntt(b, len * 2, 1);
    	for (int i = 0; i < len * 2; i++)
    		a[i] = a[i] * (long long)b[i] % p;
    	ntt(a, len * 2, -1);
    	poly_intergal(a, len);
    	for (int i = len; i < len * 2; i++)
    		a[i] = 0;
    	delete []b;
    }
    
    //这里本来应该打二次剩余的,但是因为那道题只有常数项为1的情况,就写了暴力枚举了
    int mod_sqrt(int x)
    {
    	for (int i = 0; i < p; i++) if (i * (long long)i % p == x) return x;
    	printf("No Solution
    ");
    	return 0;
    }
    
    void poly_sqrt(int *a, int len)
    {
    	if (len == 1) { a[0] = mod_sqrt(a[0]); return; }
    	int len1 = len / 2;
    	int *f0 = new int[len * 2];
    	for (int i = 0; i < len1; i++) f0[i] = a[i];
    	for (int i = len1; i < len * 2; i++) f0[i] = 0;
    	poly_sqrt(f0, len1);
    	for (int i = len1; i < len * 2; i++) f0[i] = 0;
    	int *tmp = new int[len * 2];
    	for (int i = 0; i < len * 2; i++) tmp[i] = f0[i] * 2 % p;
    	poly_inv(tmp, len);
    	ntt(f0, len * 2, 1);
    	for (int i = 0; i < len * 2; i++) f0[i] = f0[i] * (long long)f0[i] % p;
    	ntt(f0, len * 2, -1);
    	for (int i = 0; i < len; i++) f0[i] = (f0[i] + a[i]) % p;
    	ntt(f0, len * 2, 1);
    	for (int i = len; i < 2 * len; i++) tmp[i] = 0;
    	ntt(tmp, len * 2, 1);
    	for (int i = 0; i < len * 2; i++) a[i] = tmp[i] * (long long)f0[i] % p;
    	ntt(a, len * 2, -1);
    	for (int i = len; i < len * 2; i++) a[i] = 0;
    	delete []tmp;
    	delete []f0;
    }
    
    void poly_exp(int *a, int len)
    {
    	if (len == 1) { a[0]++; return; }
    	int len1 = len / 2;
    	int *f0 = new int[len * 2];
    	for (int i = 0; i < len1; i++) f0[i] = a[i];
    	for (int i = len1; i < len * 2; i++) f0[i] = 0;
    	poly_exp(f0, len1);
    	for (int i = len1; i < len * 2; i++) f0[i] = 0;
    	int *lnf0 = new int[len * 2];
    	for (int i = 0; i < len * 2; i++) lnf0[i] = f0[i];
    	poly_ln(lnf0, len);
    	a[0]++;
    	for (int i = 0; i < len; i++)
    	{
    		a[i] -= lnf0[i];
    		if (a[i] < 0) a[i] += p;
    	}
    	ntt(a, len * 2, 1);
    	ntt(f0, len * 2, 1);
    	for (int i = 0; i < len * 2; i++) a[i] = a[i] * (long long)f0[i] % p;
    	ntt(a, len * 2, -1);
    	for (int i = len; i < len * 2; i++) a[i] = 0;
    }
    
    void poly_qpow(int *a, int len, int n)
    {
    	int *tmp = new int[len * 2];
    	for (int i = 0; i < len * 2; i++) tmp[i] = i >= len ? 0 : a[i], a[i] = (i == 0);
    	while (n > 0)
    	{
    		ntt(tmp, len * 2, 1);
    		if (n & 1)
    		{
    			ntt(a, len * 2, 1);
    			for (int i = 0; i < len * 2; i++) a[i] = a[i] * (long long)tmp[i] % p;
    			ntt(a, len * 2, -1);
    			for (int i = len; i < len * 2; i++) a[i] = 0;
    		}
    		for (int i = 0; i < len * 2; i++) tmp[i] = tmp[i] * (long long)tmp[i] % p;
    		ntt(tmp, len * 2, -1);
    		for (int i = len; i < len * 2; i++) tmp[i] = 0;
    		n >>= 1;
    	}
    	delete []tmp;
    }
    
    int lagrange_inversion(int *aa, int len, int n)
    {
    	int *a = new int[len * 2];
    	for (int i = 0; i < len; i++) a[i] = aa[i];
    	for (int i = len; i < len * 2; i++) a[i] = 0;
    	for (int i = 1; i < len; i++) a[i - 1] = a[i];
    	poly_inv(a, len);
    	poly_qpow(a, len, n);
    	int ans = a[n - 1] * (long long)qpow(n, p - 2) % p;
    	delete []a;
    	return ans;
    }
    
    int a[1000000], n, len = 1;
    
    int main()
    {
    	scanf("%d", &n); for (int i = 0; i < n; i++) scanf("%d", &a[i]);
    	while (len < n) len *= 2;
    	poly_exp(a, len);
    	for (int i = 0; i < n; i++) printf("%d ", a[i]);
    	return 0;
    }
    
    
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  • 原文地址:https://www.cnblogs.com/oier/p/10289877.html
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