本文主要是介绍【清华夏令营模拟2019.5.22】连续段(析合树+多项式牛顿迭代),希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
Description:
n<=1e5,P是NTT模数
题解:
析合树见WC2019LCA营员交流讲稿
我们考虑把一个序列划分成本源连续段。
怎么划分呢?就是极大划分,假设划分成了x段。
这x段需要满足任取一个区间的段,要么可以全部可以拼起来(1),要么除了最大的那一个其它都不行(2)。
仔细思考这样就能表示所有的段了。
(1)就是析点,(2)就是合点。
考虑x=2、3时只能是合点
设F表示答案序列的生成函数
所以不难列出这样的方程:
( ∑ i = 2 ∞ F i ) ∗ 2 − F 2 − F 3 = F − x (\sum_{i=2}^∞F^i)*2-F^2-F^3=F-x (∑i=2∞Fi)∗2−F2−F3=F−x
F 2 1 − F − F 2 − F 3 = F − x {F^2 \over 1-F}-F^2-F^3=F-x 1−FF2−F2−F3=F−x
F 4 + 2 ∗ F 2 − ( 1 + x ) F + x = 0 F^4+2*F^2-(1+x)F+x=0 F4+2∗F2−(1+x)F+x=0
那么用牛顿迭代去解方程就行了
Code:
#include<bits/stdc++.h>
#define fo(i, x, y) for(int i = x, B = y; i <= B; i ++)
#define ff(i, x, y) for(int i = x, B = y; i < B; i ++)
#define fd(i, x, y) for(int i = x, B = y; i >= B; i --)
#define ul unsigned long long
#define ll long long
#define pp printf
using namespace std;int n, mo, g;ll ksm(ll x, ll y) {ll s = 1;for(; y; y /= 2, x = x * x % mo)if(y & 1) s = s * x % mo;return s;
}const int N = 4e5 + 5;int r[N];
void dft(ll *a, int n, int F) {ff(i, 0, n) {r[i] = r[i / 2] / 2 + (i & 1) * (n / 2);if(i < r[i]) swap(a[i], a[r[i]]); }for(int h = 1; h < n; h *= 2) {ll wn = ksm(ksm(g, (mo - 1) / 2 / h), F == 1 ? 1 : mo - 2);for(int j = 0; j < n; j += 2 * h) {ll w = 1, b, *l = a + j, *r = a + j + h;ff(i, 0, h) {b = *r * w, *r = (*l - b) % mo, *l = (*l + b) % mo;w = w * wn % mo, l ++, r ++;}}}if(F == -1) {ll v = ksm(n, mo - 2);ff(i, 0, n) a[i] = (a[i] + mo) * v % mo;}
}
ll a0[N], a1[N];
typedef vector<ll> V;
#define pb push_back
#define si size()
V operator +(V a, V b) {a.resize(max(a.si, b.si));ff(i, 0, b.si) a[i] = (a[i] + b[i]) % mo;return a;
}
V operator -(V a, V b) {a.resize(max(a.si, b.si));ff(i, 0, b.si) a[i] = (a[i] - b[i] + mo) % mo;return a;
}
V operator *(V a, ll b) {ff(i, 0, a.si) a[i] = a[i] * b % mo;return a;
}
V operator *(V a, V b) {int n0 = a.si + b.si - 1, n = 1;while(n < n0) n *= 2;ff(i, 0, n) a0[i] = a1[i] = 0;ff(i, 0, a.si) a0[i] = a[i];ff(i, 0, b.si) a1[i] = b[i];dft(a0, n, 1); dft(a1, n, 1);ff(i, 0, n) a0[i] = a0[i] * a1[i] % mo;dft(a0, n, -1);a.resize(n0);ff(i, 0, n0) a[i] = a0[i];return a;
}
void dft(V &a, int F) {ff(i, 0, a.si) a0[i] = a[i];dft(a0, a.si, F);ff(i, 0, a.si) a[i] = a0[i];
}
V a, b;
V qni(V a) {int n0 = 1; while(n0 < a.si) n0 *= 2;V b; b.resize(1); b[0] = ksm(a[0], mo - 2);for(int n = 2; n <= n0; n *= 2) {V c = a; c.resize(n); c.resize(2 * n);b.resize(2 * n);dft(c, 1); dft(b, 1);ff(i, 0, 2 * n) b[i] = (2 * b[i] - c[i] * b[i] % mo * b[i]) % mo;dft(b, -1); b.resize(n);}b.resize(a.si); return b;
}
V yy(V a) {fd(i, a.si - 1, 1) a[i] = a[i - 1];a[0] = 0;return a;
}
V dd(int n0) {V a; a.resize(1); a[0] = 0;for(int n = 2; n <= n0; n *= 2) {V c; c.resize(2); c[0] = 0; c[1] = 1;V d; d.resize(2); d[0] = -1; d[1] = -1;V b = a; b.resize(n);c = c - b - yy(b);d = d + b * 4;b = b * a; b.resize(n);c = c + b * 2;b = b * a; b.resize(n);d = d + b * 4;b = b * a; b.resize(n);c = c + b;c = c * qni(d); c.resize(n);a.resize(n); a = a - c;}return a;
}int main() {freopen("b.in", "r", stdin);freopen("b.out", "w", stdout);scanf("%d %d", &n, &mo);for(g = 2; ; g ++) {if(ksm(g, (mo - 1) / 2) != 1) break;}
/*n = 10;a.resize(n + 1);fo(i, 0, n) a[i] = i + 1;b = qni(a);a = a * b;ff(i, 0, n) pp("%lld ", a[i]); pp("\n");return 0;*/int n0 = 1; while(n0 <= n) n0 *= 2;a = dd(n0);fo(i, 1, n) pp("%lld\n", a[i]);
}
这篇关于【清华夏令营模拟2019.5.22】连续段(析合树+多项式牛顿迭代)的文章就介绍到这儿,希望我们推荐的文章对编程师们有所帮助!