Submission #34636438

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Source Code Expand

#include<bits/stdc++.h>
#ifdef xay5421
#define D(...) fprintf(stderr,__VA_ARGS__)
#define DD(...) D(#__VA_ARGS__ "="),debug_helper::debug(__VA_ARGS__),D("\n")
#include"/home/xay5421/debug.hpp"
#else
#define D(...) ((void)0)
#define DD(...) ((void)0)
#endif
#define pb push_back
#define eb emplace_back
#define SZ(x) ((int)(x).size())
#define each(x,v) for(auto&x:v)
#define rep(i,a,b) for(int i=(a);i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>=(b);--i)
template<class T>void rd(T&x){int f=0,c;while(!isdigit(c=getchar()))f^=!(c^45);x=(c&15);while(isdigit(c=getchar()))x=x*10+(c&15);if(f)x=-x;}
template<class T>void pt(T x,int c=-1){if(x<0)putchar('-'),x=-x;if(x>9)pt(x/10);putchar(x%10+48);if(c!=-1)putchar(c);}
using namespace std;
using LL=long long;
using ULL=unsigned long long;
const int P=998244353;
int ad(int k1,int k2){return k1+k2>=P?k1+k2-P:k1+k2;}
int su(int k1,int k2){return k1-k2<0?k1-k2+P:k1-k2;}
int mu(int k1,int k2){return 1ULL*k1*k2%P;}
void uad(int&k1,int k2){(k1+=k2)>=P&&(k1-=P);}
void usu(int&k1,int k2){(k1-=k2)<0&&(k1+=P);}
template<class... T>int ad(int k1,T... k2){return ad(k1,ad(k2...));}
template<class... T>int su(int k1,T... k2){return su(k1,ad(k2...));}
template<class... T>int mu(int k1,T... k2){return mu(k1,mu(k2...));}
template<class... T>void uad(int&k1,T... k2){return uad(k1,ad(k2...));}
template<class... T>void usu(int&k1,T... k2){return usu(k1,ad(k2...));}
int po(int k1,int k2){
	int k3=1;
	for(;k2;k2>>=1,k1=mu(k1,k1))if(k2&1)k3=mu(k3,k1);
	return k3;
}
const int N=5005;
int n,K,a[N],fac[N],ifac[N];
int C(int n,int m){
	if(m<0||n<m)return 0;
	return mu(fac[n],ifac[m],ifac[n-m]);
}
int dp[N],new_dp[N];
void push(int x){
	memset(new_dp,0,sizeof(new_dp));
	rep(i,0,n)if(dp[i]){
		for(int j=0;j<=x&&j<=i;++j){
			uad(new_dp[i+x-j],mu(fac[x],dp[i],C(i,j),C(i+x-j,x-j)));
		}
	}
	memcpy(dp,new_dp,sizeof(dp));
}
int main(){
	fac[0]=1;
	rep(i,1,N-1)fac[i]=mu(fac[i-1],i);
	ifac[N-1]=po(fac[N-1],P-2);
	per(i,N-1,1)ifac[i-1]=mu(ifac[i],i);
	rd(n),rd(K);
	rep(i,1,n)rd(a[i]);
	sort(a+1,a+n+1);
	dp[0]=1;
	for(int i=1,j;i<=n;i=j){
		j=i+1;
		while(j<=n&&a[i]==a[j])++j;
		push(j-i);
	}
	reverse(dp+1,dp+n+1);
	per(i,n,1){
		rep(j,i+1,n){
			usu(dp[i],mu(dp[j],C(j-1,i-1)));
		}
	}
	printf("%d\n",dp[K+1]);
	return 0;
}

Submission Info

Judge Result