Submission #68725986

---

Source Code Expand

#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<vvvl> vvvvl;
typedef vector<bool> vb;
typedef vector<vb> vvb;
typedef vector<vvb> vvvb;
typedef vector<vvvb> vvvvb;
typedef pair<ll,ll> pl;
typedef pair<ll,pl> ppl;
typedef pair<ll,ppl> pppl;
typedef pair<ll,pppl> pppppl;
#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(b)-1;i>=(a);i--)
#define all(a) begin(a),end(a)
#define sz(a) (int)(a).size()
#define F first
#define S second
#define bs(A,x) binary_search(all(A),x)
#define lb(A,x) (ll)(lower_bound(all(A),x)-A.begin())
#define ub(A,x) (ll)(upper_bound(all(A),x)-A.begin())
#define cou(A,x) (ll)(upper_bound(all(A),x)-lower_bound(all(A),x))
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}
//*
using mint=modint998244353;
const ll mod=998244353;
//*/
/*
using mint=modint1000000007;
const ll mod=1000000007;
//*/
//using mint=modint;
//*
typedef vector<mint> vm;
typedef vector<vm> vvm;
typedef vector<vvm> vvvm;
typedef vector<vvvm> vvvvm;
ostream&operator<<(ostream&os,mint a){os<<a.val();return os;}
istream&operator>>(istream&is,mint&a){int x;is>>x;a=mint(x);return is;}
//*/
template<typename T1,typename T2>ostream&operator<<(ostream&os,pair<T1,T2>p){os<<p.F<<" "<<p.S;return os;}
template<typename T1,typename T2>istream&operator>>(istream&is,pair<T1,T2>&p){is>>p.F>>p.S;return is;}
template<typename T>ostream&operator<<(ostream&os,vector<T>v){rep(i,0,sz(v))os<<v[i]<<(i+1!=sz(v)?" ":"");return os;}
template<typename T>istream&operator>>(istream&is,vector<T>&v){for(T&in:v)is>>in;return is;}
int main(){
  cin.tie(0)->sync_with_stdio(0);
  cin.exceptions(cin.failbit);
  ll N,K,X;cin>>N>>K>>X;
  vm ex(2e6,1),re(2e6);
  rep(i,1,2e6)ex[i]=i*ex[i-1];
  rep(i,0,2e6)re[i]=1/ex[i];
  vvvm DP(300,vvm(300,vm(300)));
  vvvb seen(300,vvb(300,vb(300)));
  
  vm C(2e6);
  rep(i,1,2e6)C[i]=C[i-1]+ex[i-1+N-1]*re[N-1]*re[i-1];
  function<mint(ll,ll,ll)>f=[&](ll K,ll a,ll b)->mint{
    assert(a+X<b+X+1);
    if(K==1)return C[b+X+1]-C[a+X];
    if(!seen[K][a][b]){
      rep(x,0,N+1){
        ll _a=max(0ll,X+a-x);
        ll _b=max(0ll,X+1+b-x);
        _a=(_a+1)/2;
        _b=(_b+1)/2;
        DP[K][a][b]+=ex[N]*re[x]*re[N-x]*f(K-1,_a,_b);
      }
      seen[K][a][b]=1;
    }
    return DP[K][a][b];
  };
  cout<<f(K,0,0)<<endl;
  return 0;
}

Submission Info

Judge Result