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QOJ
ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#693633 | #6736. Alice and Bob | NULL_SF | WA | 1ms | 5732kb | C++23 | 758b | 2024-10-31 16:29:57 | 2024-10-31 16:29:59 |
Judging History
answer
#include <iostream>
#define int long long
using namespace std;
const int mod=998244353;
int pre[10000001],inv[10000001];
int quick_pow(int base,int index)
{
int ans=1,tmp=base%mod;
while(index){
if(index&1){
ans*=tmp;
ans%=mod;
}
tmp*=tmp;
tmp%=mod;
index>>=1;
}
return ans;
}
int get_inv(int x)
{
return quick_pow(x,mod-2);
}
int get_C(int down,int up)
{
return pre[down]*inv[up]%mod*inv[down-up]%mod;
}
signed main()
{
int n;
cin>>n;
pre[0]=inv[0]=1;
for(int i=1;i<=n;i++){
pre[i]=pre[i-1]*i%mod;
inv[i]=inv[i-1]*get_inv(i)%mod;
}
int ans=0;
for(int i=1;i<=(n+1)/2;i++){
ans+=pre[n-i]*get_C(n-i,i-1)%mod;
ans%=mod;
}
cout<<ans;
return 0;
}
詳細信息
Test #1:
score: 100
Accepted
time: 1ms
memory: 5548kb
input:
1
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 0
Accepted
time: 1ms
memory: 5732kb
input:
2
output:
1
result:
ok 1 number(s): "1"
Test #3:
score: -100
Wrong Answer
time: 1ms
memory: 5672kb
input:
10
output:
806280
result:
wrong answer 1st numbers differ - expected: '997920', found: '806280'