Comet OJ - Contest #2 (D 错综的光影所迷惑的思念是) 容斥计数

#include <bits/stdc++.h>  
#define N 4010 
#define ll long long 
#define mod 998244353    
#define setIO(s) freopen(s".in","r",stdin) 
using namespace std;  
int edges,now,n;  
int hd[N<<1],to[N<<2],nex[N<<2],cnt[N<<1][N],sum[N],bin[N],ans[N];      
void add(int u,int v) 
{
    nex[++edges]=hd[u],hd[u]=edges,to[edges]=v;    
}
void dfs(int u,int ff,int d) 
{
    if(u<=n) ++sum[d], ++cnt[now][d];        
    for(int i=hd[u];i;i=nex[i]) if(to[i]!=ff) dfs(to[i], u, d+1); 
}
int main() 
{  
    // setIO("input");  
    int i,j;  
    scanf("%d",&n);   
    bin[0]=1; 
    for(i=1;i<=n;++i) bin[i]=bin[i-1]*2%mod; 
    for(i=1;i<n;++i) 
    {
        int u,v; 
        scanf("%d%d",&u,&v);    
        add(u,i+n),add(i+n,u);
        add(i+n,v),add(v,i+n);           
    }  
    for(i=1;i<=2*n;++i) 
    {
        now=0;   
        for(j=hd[i];j;j=nex[j]) ++now, dfs(to[j],i,1);         
        int re=(i<=n);     
        for(j=1;j<n;++j) 
        {
            int mdl=bin[sum[j]]-1;   
            for(int k=1;k<=now;++k) 
            {
                (mdl+=mod-bin[cnt[k][j]]+1)%=mod;   
            }    
            (ans[j]+=(ll)mdl*bin[re]%mod)%=mod;    
            re+=sum[j];   
        }
        memset(sum,0,sizeof sum);   
        for(j=1;j<=now;++j) memset(cnt[j], 0, sizeof cnt[j]);    
    }
    for(i=1;i<n;++i) 
        printf("%d\n",(ans[i]+mod)%mod);    
    return 0;   
}