QOJ.ac
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 |
---|---|---|---|---|---|---|---|---|---|
#142337 | #6736. Alice and Bob | LeticiaFCS | AC ✓ | 242ms | 81368kb | C++20 | 3.3kb | 2023-08-18 23:36:19 | 2023-08-18 23:36:22 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
using ll = int64_t;
const ll MOD = 998244353;
int minv(int a, int m) {
a %= m; //assert(a);
return a == 1 ? 1 : int(m - int64_t(minv(m, a)) * m / a);
}
template<unsigned M_> struct modnum {
static constexpr unsigned M = M_;
using ll = int64_t; using ull = uint64_t; unsigned x;
modnum& norm(unsigned a) { x = a < M ? a : a - M; return *this; }
constexpr modnum(ll a = 0U) : x(unsigned((a %= ll(M)) < 0 ? a + ll(M) : a)) {}
explicit operator int() const { return x; }
modnum& operator+=(const modnum& a) { return norm(x + a.x); }
modnum& operator-=(const modnum& a) { return norm(x - a.x + M); }
modnum& operator*=(const modnum& a) { x = unsigned(ull(x) * a.x % M); return *this; }
modnum& operator/=(const modnum& a) { return (*this *= a.inv()); }
modnum operator+(const modnum& a) const { return (modnum(*this) += a); }
modnum operator-(const modnum& a) const { return (modnum(*this) -= a); }
modnum operator*(const modnum& a) const { return (modnum(*this) *= a); }
modnum operator/(const modnum& a) const { return (modnum(*this) /= a); }
template<typename T> friend modnum operator+(T a, const modnum& b) { return (modnum(a) += b); }
template<typename T> friend modnum operator-(T a, const modnum& b) { return (modnum(a) -= b); }
template<typename T> friend modnum operator*(T a, const modnum& b) { return (modnum(a) *= b); }
template<typename T> friend modnum operator/(T a, const modnum& b) { return (modnum(a) /= b); }
modnum operator+() const { return *this; }
modnum operator-() const { return modnum() - *this; }
modnum pow(ll e) const {
if (e < 0) return inv().pow(-e);
modnum b = x, xe = 1U;
for (; e; e >>= 1) { if (e & 1) xe *= b; b *= b; }
return xe;
}
modnum inv() const { return minv(x, M); }
friend modnum inv(const modnum& a) { return a.inv(); }
explicit operator bool() const { return x; }
friend bool operator==(const modnum& a, const modnum& b) { return a.x == b.x; }
friend bool operator!=(const modnum& a, const modnum& b) { return a.x != b.x; }
friend ostream &operator<<(ostream& os, const modnum& a) { return os << a.x; }
friend istream &operator>>(istream& in, modnum& n) { ll v_; in >> v_; n = modnum(v_); return in; }
};
using num = modnum<998244353>;
int minv_2(int a) {
static const int m = MOD;
return a <= 1 ? a : m - int64_t(minv_2(m % a)) * (m / a) % m;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n; cin>>n;
if(n <= 2){
cout<<"1\n";
return 0;
}
vector<ll> inv(n+1);
/*
5, MOD
MOD, 5
*/
inv[1] = 1;
for (int x = 2; x <= n; ++x) {
inv[x] = -(MOD/x * inv[MOD % x])%MOD;
inv[x] += MOD;
inv[x] %= MOD;
//cout<<x<<" "<<inv[x]<<" "<<minv(x, MOD)<<" "<<minv_2(x)<<"\n";
}
num fact = 1; // (n-1)!
for(int i =1; i <= n - 2; i++)
fact *= i;
num ans = fact*(n-1);
num big = n-2;
ans = ans + big*fact;
for(int i = 3; i < n; i++){
int x = i + i - 1;
big = big *inv[(n-(i-1))];
big = big * (n-(x-1)) * (n - (x-2));
fact = fact * inv[(n-(i-1))];
ans = ans + big*fact;
}
cout<<ans<<"\n";
return 0;
}
詳細信息
Test #1:
score: 100
Accepted
time: 1ms
memory: 3532kb
input:
1
output:
1
result:
ok 1 number(s): "1"
Test #2:
score: 0
Accepted
time: 1ms
memory: 3512kb
input:
2
output:
1
result:
ok 1 number(s): "1"
Test #3:
score: 0
Accepted
time: 1ms
memory: 3456kb
input:
10
output:
997920
result:
ok 1 number(s): "997920"
Test #4:
score: 0
Accepted
time: 1ms
memory: 3524kb
input:
100
output:
188898954
result:
ok 1 number(s): "188898954"
Test #5:
score: 0
Accepted
time: 1ms
memory: 3520kb
input:
4
output:
10
result:
ok 1 number(s): "10"
Test #6:
score: 0
Accepted
time: 1ms
memory: 3528kb
input:
8
output:
12336
result:
ok 1 number(s): "12336"
Test #7:
score: 0
Accepted
time: 1ms
memory: 3452kb
input:
16
output:
373118483
result:
ok 1 number(s): "373118483"
Test #8:
score: 0
Accepted
time: 1ms
memory: 3492kb
input:
32
output:
314585464
result:
ok 1 number(s): "314585464"
Test #9:
score: 0
Accepted
time: 1ms
memory: 3456kb
input:
64
output:
627827331
result:
ok 1 number(s): "627827331"
Test #10:
score: 0
Accepted
time: 1ms
memory: 3492kb
input:
128
output:
828497685
result:
ok 1 number(s): "828497685"
Test #11:
score: 0
Accepted
time: 1ms
memory: 3448kb
input:
256
output:
65697890
result:
ok 1 number(s): "65697890"
Test #12:
score: 0
Accepted
time: 1ms
memory: 3576kb
input:
512
output:
854187619
result:
ok 1 number(s): "854187619"
Test #13:
score: 0
Accepted
time: 1ms
memory: 3460kb
input:
1024
output:
513823539
result:
ok 1 number(s): "513823539"
Test #14:
score: 0
Accepted
time: 32ms
memory: 13876kb
input:
1361956
output:
617368199
result:
ok 1 number(s): "617368199"
Test #15:
score: 0
Accepted
time: 176ms
memory: 62440kb
input:
7579013
output:
827172636
result:
ok 1 number(s): "827172636"
Test #16:
score: 0
Accepted
time: 194ms
memory: 66696kb
input:
8145517
output:
710624331
result:
ok 1 number(s): "710624331"
Test #17:
score: 0
Accepted
time: 138ms
memory: 51192kb
input:
6140463
output:
707600568
result:
ok 1 number(s): "707600568"
Test #18:
score: 0
Accepted
time: 74ms
memory: 30684kb
input:
3515281
output:
698302413
result:
ok 1 number(s): "698302413"
Test #19:
score: 0
Accepted
time: 159ms
memory: 57552kb
input:
6969586
output:
69470392
result:
ok 1 number(s): "69470392"
Test #20:
score: 0
Accepted
time: 61ms
memory: 25600kb
input:
2888636
output:
433579983
result:
ok 1 number(s): "433579983"
Test #21:
score: 0
Accepted
time: 239ms
memory: 81368kb
input:
9999998
output:
758172780
result:
ok 1 number(s): "758172780"
Test #22:
score: 0
Accepted
time: 234ms
memory: 81292kb
input:
9999999
output:
605195495
result:
ok 1 number(s): "605195495"
Test #23:
score: 0
Accepted
time: 242ms
memory: 81256kb
input:
10000000
output:
866813682
result:
ok 1 number(s): "866813682"