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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#360783 | #6736. Alice and Bob | 1366397866 | TL | 0ms | 0kb | C++14 | 1.5kb | 2024-03-22 08:48:18 | 2024-03-22 08:48:19 |
answer
#include<bits/stdc++.h>
using namespace std;
#define endl "\n"
#define PII pair<int,int>
#define int long long
const int N=1e7+10;
const int INF=1e18;
namespace DEBUG {
template <typename T>
void _debug(const char* format, T t) {
cerr << format << '=' << t << endl;
}
template <class First, class... Rest>
void _debug(const char* format, First first, Rest... rest) {
while (*format != ',') cerr << *format++;
cerr << '=' << first << ",";
_debug(format + 1, rest...);
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& V) {
os << "[ ";
for (const auto& vv : V) os << vv << ", ";
os << "]";
return os;
}
#define debug(...) _debug(#__VA_ARGS__, __VA_ARGS__)
} // namespace DEBUG
using namespace DEBUG;
const int mod=998244353;
int jc[N],invjc[N];
int q_pow(int a, int k, int p) {
int res = 1;
while (k) {
if (k & 1) res = res * a % p;
a = a * a % p;
k >>= 1;
}
return res;
}
void init()
{
jc[0]=1;
invjc[0]=1;
for(int i=1;i<N;i++)
{
jc[i]=jc[i-1]*i%mod;
invjc[i]=invjc[i-1]*q_pow(i,mod-2,mod)%mod;
}
}
int C(int a,int b)
{
if(a<b)return 0;
return jc[a]*invjc[b]%mod*invjc[a-b]%mod;
}
void solve()
{
int n;
cin>>n;
int sum=0;
for(int i=1;i<=n;i++)
{
if(n-i<i-1)break;
sum=(sum+(C(n-i,i-1)*jc[i-1]%mod*jc[n-i]%mod))%mod;
}
cout<<sum%mod<<endl;
}
signed main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int T=1;
init();
// cin>>T;
while(T--)solve();
return 0;
}
Details
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Test #1:
score: 0
Time Limit Exceeded
input:
1
output:
1