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ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#487021 | #6410. Classical DP Problem | ucup-team1525# | WA | 7ms | 103524kb | C++20 | 2.1kb | 2024-07-22 15:20:50 | 2024-07-22 15:20:52 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
using ll=long long;
const int N=5e3;
const int mod=998244353;
int fac[N+5],ifac[N+5];
int add(int x,int y){ return (x+=y)>=mod?x-mod:x; }
int sub(int x,int y){ return (x-=y)<0?x+mod:x; }
int ksm(ll x,int tp,int s=1){
for(;tp;x=x*x%mod,tp>>=1) if(tp&1) s=x*s%mod;
return s;
}
void prep(){
fac[0]=1;
for(int i=1;i<=N;i++) fac[i]=1ll*fac[i-1]*i%mod;
ifac[N]=ksm(fac[N],mod-2);
for(int i=N;i;i--) ifac[i-1]=1ll*ifac[i]*i%mod;
}
int C(int n,int m){
return n<0||m<0||n<m?0:1ll*fac[n]*ifac[m]%mod*ifac[n-m]%mod;
}
int n;
int a[N+5];
int r,s;
int work1(int c0,int c1,int c2){
static int f[N+5][N+5];
memset(f,0,sizeof f);
int x=a[c0];
f[0][0]=1;
for(int i=1;i<=c2;i++){
int h=a[c0+i];
for(int j=0;j<=min(i,x);j++){
f[i][j]=1ll*(h-x+j)*f[i-1][j]%mod;
if(j) f[i][j]=(f[i][j]+1ll*(x-j+1)*f[i-1][j-1])%mod;
}
}
return f[c2][x];
}
void work2(int c0,int c1,int c2){
static int f[N+5][N+5],c[N+5];
for(int i=1;i<=c0+c1;i++)
c[a[i]]++;
for(int j=n;j;j--) c[j]+=c[j+1];
f[0][0]=1;
for(int i=1;i<=r;i++)
for(int j=0;j<=min(r-c2,i);j++){
f[i][j]=f[i-1][j];
if(j) f[i][j]=(f[i][j]+1ll*c[i]*f[i-1][j-1])%mod;
}
for(int c=c2;c<=r;c++){
int t=0;
for(int i=0;i<=c2;i++){
if(c2-i&1) t=sub(t,ksm(i,c,C(c2,i)));
else t=add(t,ksm(i,c,C(c2,i)));
}
s=(s+1ll*f[r][r-c]*(t+mod))%mod;
}
if(c1+c2==r){
s=add(s,sub(work1(c0,0,n-c0),fac[r]));
}
}
int main(){
prep();
scanf("%d",&n);
for(int i=1;i<=n;i++)
scanf("%d",&a[i]);
for(int i=n;i;i--)
if(a[i]<=n-i){
r=n-i;
break;
}
int c0,c1,c2; c0=c1=c2=0;
for(int i=1;i<=n;i++)
if(a[i]<r) c0++;
else if(a[i]==r) c1++;
else c2++;
if(c1==0){
s=work1(c0,c1,c2);
}
else{
work2(c0,c1,c2);
}
printf("%d %d\n",r,s);
return 0;
}
Details
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Test #1:
score: 100
Accepted
time: 3ms
memory: 102684kb
input:
3 1 2 3
output:
2 6
result:
ok 2 number(s): "2 6"
Test #2:
score: -100
Wrong Answer
time: 7ms
memory: 103524kb
input:
1 1
output:
0 1
result:
wrong answer 1st numbers differ - expected: '1', found: '0'