QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#774153 | #8635. 圆 | zyxawa | 100 ✓ | 119ms | 199292kb | C++14 | 1.4kb | 2024-11-23 12:08:18 | 2024-11-23 12:08:18 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int n,a[11],v[11];
ll s,pre[5001]={1},f[5001][5001],g[5001];
const int mod=998244353;
ll qpow(ll a,ll b){
ll s=1;
for(;b;b>>=1,a=a*a%mod) if(b&1) s=s*a%mod;
return s;
}
void dfs(int x){
if(x==n+1){
bitset <11> b;
for(int i=1;i<=n;i++){
b[a[i]]=b[a[i]%n+1]=b[(a[i]+n-2)%n+1]=1;
if(b.count()==n) return (void)(s+=i);
}
}
for(int i=1;i<=n;i++) if(!v[i]) a[x]=i,v[i]=1,dfs(x+1),v[i]=0;
}
void dp(){
for(int i=3;i<n;i++) for(int j=1;j<=i;j++) (f[i][j]+=f[i-1][j-1]+f[i-2][j-1]+f[i-3][j-1])%=mod;
}
int main(){
scanf("%d",&n);
for(int i=1;i<=n;i++) pre[i]=pre[i-1]*i%mod;
if(n<=8) return dfs(1),printf("%lld",s*qpow(pre[n],mod-2)%mod),0;
memset(f,0,sizeof(f)),f[2][0]=1,dp();
for(int i=0;i<n;i++) (g[i+1]+=f[n-1][i])%=mod;
memset(f,0,sizeof(f)),f[2][1]=f[3][1]=f[4][1]=1,dp();
for(int i=0;i<n;i++) (g[i+1]+=f[n-1][i]+f[n-2][i])%=mod;
memset(f,0,sizeof(f)),f[2][1]=f[3][1]=1,dp();
for(int i=0;i<n;i++) (g[i+1]+=f[n-1][i]+f[n-2][i]+f[n-3][i])%=mod;
memset(f,0,sizeof(f)),f[2][2]=f[3][2]=f[4][2]=1,dp();
for(int i=0;i<n;i++) (g[i+1]+=f[n-1][i]+f[n-2][i]+f[n-3][i])%=mod;
for(int i=1;i<=n;i++) (s+=g[i]*pre[i]%mod*pre[n-i])%=mod;
printf("%lld",(pre[n]*(n+1)-s+mod)%mod*qpow(pre[n],mod-2)%mod);
return 0;
}
Details
Tip: Click on the bar to expand more detailed information
Pretests
Final Tests
Test #1:
score: 10
Accepted
time: 0ms
memory: 3824kb
input:
3
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 10
Accepted
time: 0ms
memory: 3880kb
input:
4
output:
2
result:
ok 1 number(s): "2"
Test #3:
score: 10
Accepted
time: 1ms
memory: 3736kb
input:
6
output:
299473309
result:
ok 1 number(s): "299473309"
Test #4:
score: 10
Accepted
time: 59ms
memory: 199176kb
input:
10
output:
487238321
result:
ok 1 number(s): "487238321"
Test #5:
score: 10
Accepted
time: 56ms
memory: 199292kb
input:
100
output:
41620761
result:
ok 1 number(s): "41620761"
Test #6:
score: 10
Accepted
time: 53ms
memory: 199180kb
input:
200
output:
208771764
result:
ok 1 number(s): "208771764"
Test #7:
score: 10
Accepted
time: 47ms
memory: 199184kb
input:
500
output:
888621375
result:
ok 1 number(s): "888621375"
Test #8:
score: 10
Accepted
time: 115ms
memory: 199272kb
input:
4798
output:
319137015
result:
ok 1 number(s): "319137015"
Test #9:
score: 10
Accepted
time: 117ms
memory: 199208kb
input:
4999
output:
818467659
result:
ok 1 number(s): "818467659"
Test #10:
score: 10
Accepted
time: 119ms
memory: 199236kb
input:
5000
output:
142907477
result:
ok 1 number(s): "142907477"