F - Many Easy Problems
Time limit : 5sec / Memory limit : 512MB
Score : 1900 points
Problem Statement
One day, Takahashi was given the following problem from Aoki:
- You are given a tree with N vertices and an integer K. The vertices are numbered 1 through N. The edges are represented by pairs of integers (ai,bi).
- For a set S of vertices in the tree, let f(S) be the minimum number of the vertices in a subtree of the given tree that contains all vertices in S.
- There are ways to choose K vertices from the trees. For each of them, let S be the set of the chosen vertices, and find the sum of f(S) over all ways.
- Since the answer may be extremely large, print it modulo 924844033(prime).
Since it was too easy for him, he decided to solve this problem for all K=1,2,…,N.
Constraints
- 2≦N≦200,000
- 1≦ai,bi≦N
- The given graph is a tree.
Input
The input is given from Standard Input in the following format:
N a1 b1 a2 b2 : aN−1 bN−1
Output
Print N lines. The i-th line should contain the answer to the problem where K=i, modulo 924844033.
大意:从一棵树中选择$k$个点,记$f(S)$为最小的包括点集$S$的联通子图,求每个$k$的$\sum F(S)$。
思路{
直接做比较麻烦。考虑计算点的贡献。
一个点$u$被算入联通子图当且仅当选出的$k$个点没有全部在它的子树内或者是子树外。
那么用总数减去不合法方案数贡献就是$C_n^k-\sum_{i=1}^{k}C_{a_i}^k$
(其中$a_i$为删除$u$后各个连通块的大小。
对于$k$来说把这些项单独提出来,在每一个组合数的前面都会有一个系数$p_i$
则$Ans_k=\sum_{i=k}^np_i*C_i^k=\dfrac{1}{k!}*\sum_{i=k}^{n}\dfrac{p_i*i!}{(i-k)!}$
把记录$p_i*i!$的数组设为$A$,记录$\dfrac{1}{(i-k)!}$数组翻转设为$B$;
不难发现变成了一个卷积的形式,由于还要取模,直接上$NTT$做多项式乘法就好了。
}
#include<bits/stdc++.h> #define LL long long #define RG register #define il inline #define N 400010 #define mod 924844033 using namespace std; struct ed{int nxt,to;}e[N*2]; int head[N],tot,n,m,R[N*2],A[N*2],B[N*2],fac[N*2],_fac[N*2],sz[N]; void link(int u,int v){e[tot].nxt=head[u];e[tot].to=v;head[u]=tot++;} void lnk(int u,int v){link(u,v),link(v,u);} void dfs(int u,int faa){ A[n]++; sz[u]=1; for(int i=head[u];i!=-1;i=e[i].nxt){ int v=e[i].to;if(v==faa)continue; dfs(v,u);sz[u]+=sz[v]; A[sz[v]]--;if(A[sz[v]]<0)A[sz[v]]+=mod; } A[n-sz[u]]--;if(A[n-sz[u]]<0)A[n-sz[u]]+=mod; } int qp(int a,int b){ if(!b)return 1;if(a==1)return a; int temp=qp(a,(b>>1)); temp=1ll*temp*temp%mod; if(b&1)temp=1ll*temp*a%mod; return temp; } void NTT(int *a,int f){ for(int i=0;i<n;++i)if(i<R[i])swap(a[i],a[R[i]]); for(int i=1;i<n;i<<=1){ int gn=qp(5,(mod-1)/(i<<1)); for(int j=0;j<n;j+=(i<<1)){ int g=1; for(int k=0;k<i;++k,g=1ll*g*gn%mod){ int x=a[j+k],y=1ll*g*a[j+k+i]%mod; a[j+k]=(x+y)%mod; a[j+k+i]=(x-y+mod)%mod; } } } if(f==-1){ reverse(a+1,a+n); int _n=qp(n,mod-2); for(int i=0;i<n;++i)a[i]=1ll*a[i]*_n%mod; } } int main(){ memset(head,-1,sizeof(head)); scanf("%d",&n);for(int i=1;i<n;++i){int u,v;scanf("%d%d",&u,&v),lnk(u,v);} dfs(1,1); fac[1]=1;fac[0]=1; for(int i=2;i<=n;++i)fac[i]=1ll*fac[i-1]*i%mod,A[i]=1ll*A[i]*fac[i]%mod; _fac[n]=qp(fac[n],mod-2);for(int i=n;i;--i)_fac[i-1]=1ll*_fac[i]*i%mod; for(int i=1;i<=n;++i)B[i]=_fac[n-i]; m=n;int L=0; for(n=1;n<=(m<<1);n<<=1)L++; for(int i=0;i<n;++i)R[i]=(R[i>>1]>>1)|((i&1)<<(L-1)); NTT(A,1),NTT(B,1); for(int i=0;i<n;++i)A[i]=1ll*A[i]*B[i]%mod; NTT(A,-1); for(int i=1;i<=m;++i)printf("%d\n",1ll*A[m+i]*_fac[i]%mod); return 0; }
时间: 2024-11-20 12:01:20