QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#591021 | #8635. 圆 | ship2077 | 100 ✓ | 15ms | 4036kb | C++23 | 981b | 2024-09-26 13:40:45 | 2024-09-26 13:40:46 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
constexpr int M=5005,mod=998244353;
int n,ans,now,fac[M],ifac[M],dp[4][M];
int qpow(int x,int n){
int s=1; while (n){
if (n&1) s=1ll*s*x%mod;
x=1ll*x*x%mod; n>>=1;
} return s;
}
int rdc(int x){return x>=mod?x-mod:x;}
int main(){
scanf("%d",&n);
for (int i=fac[0]=1;i<=n;i++) fac[i]=1ll*fac[i-1]*i%mod;
dp[0][0]=1;
for (int i=1;i<=n;i++){
if (now) now--; else now=3;
dp[now][0]=0;
for (int j=1;j<=i;j++){
dp[now][j]=dp[(now+1)&3][j-1];
if (i>=2) dp[now][j]=rdc(dp[now][j]+dp[(now+2)&3][j-1]);
if (i>=3) dp[now][j]=rdc(dp[now][j]+dp[(now+3)&3][j-1]);
}
}
// for (int i=0;i<=n;i++) cerr<<dp[now][i]<<", ";cerr<<endl;
for (int i=1;i<=n;i++){
const int coef=i==n?fac[n]:((0ll+mod-fac[n-i])%mod*fac[i-1]%mod);
ans=(ans+1ll*dp[now][i]*coef)%mod;
}
if (ans<0) ans+=mod;
printf("%lld\n",1ll*ans*qpow(fac[n-1],mod-2)%mod);
return 0;
}
Details
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Pretests
Final Tests
Test #1:
score: 10
Accepted
time: 0ms
memory: 3948kb
input:
3
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 10
Accepted
time: 0ms
memory: 3912kb
input:
4
output:
2
result:
ok 1 number(s): "2"
Test #3:
score: 10
Accepted
time: 0ms
memory: 3900kb
input:
6
output:
299473309
result:
ok 1 number(s): "299473309"
Test #4:
score: 10
Accepted
time: 0ms
memory: 3912kb
input:
10
output:
487238321
result:
ok 1 number(s): "487238321"
Test #5:
score: 10
Accepted
time: 0ms
memory: 3812kb
input:
100
output:
41620761
result:
ok 1 number(s): "41620761"
Test #6:
score: 10
Accepted
time: 0ms
memory: 3828kb
input:
200
output:
208771764
result:
ok 1 number(s): "208771764"
Test #7:
score: 10
Accepted
time: 1ms
memory: 3924kb
input:
500
output:
888621375
result:
ok 1 number(s): "888621375"
Test #8:
score: 10
Accepted
time: 14ms
memory: 4036kb
input:
4798
output:
319137015
result:
ok 1 number(s): "319137015"
Test #9:
score: 10
Accepted
time: 15ms
memory: 3848kb
input:
4999
output:
818467659
result:
ok 1 number(s): "818467659"
Test #10:
score: 10
Accepted
time: 15ms
memory: 3904kb
input:
5000
output:
142907477
result:
ok 1 number(s): "142907477"