結果

問題 No.823 Many Shifts Easy
ユーザー ei1333333
提出日時 2019-04-26 22:13:10
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 5 ms / 2,000 ms
コード長 4,469 bytes
コンパイル時間 1,756 ms
コンパイル使用メモリ 197,688 KB
最終ジャッジ日時 2025-01-07 03:13:14
ジャッジサーバーID
(参考情報)
judge1 / judge4
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ファイルパターン 結果
other AC * 10
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ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
using int64 = long long;
const int mod = 1e9 + 7;
const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;
struct IoSetup {
IoSetup() {
cin.tie(nullptr);
ios::sync_with_stdio(false);
cout << fixed << setprecision(10);
cerr << fixed << setprecision(10);
}
} iosetup;
template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
os << p.first << " " << p.second;
return os;
}
template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
is >> p.first >> p.second;
return is;
}
template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
for(int i = 0; i < (int) v.size(); i++) {
os << v[i] << (i + 1 != v.size() ? " " : "");
}
return os;
}
template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
for(T &in : v) is >> in;
return is;
}
template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
template< typename T = int64 >
vector< T > make_v(size_t a) {
return vector< T >(a);
}
template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}
template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
t = v;
}
template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
for(auto &e : t) fill_v(e, v);
}
template< int mod >
struct ModInt {
int x;
ModInt() : x(0) {}
ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
ModInt &operator+=(const ModInt &p) {
if((x += p.x) >= mod) x -= mod;
return *this;
}
ModInt &operator-=(const ModInt &p) {
if((x += mod - p.x) >= mod) x -= mod;
return *this;
}
ModInt &operator*=(const ModInt &p) {
x = (int) (1LL * x * p.x % mod);
return *this;
}
ModInt &operator/=(const ModInt &p) {
*this *= p.inverse();
return *this;
}
ModInt &operator^=(int64_t n) {
int y = x;
x = 1;
while(n > 0) {
if(n & 1) x = 1LL * x * y % mod;
y = 1LL * y * y % mod;
n >>= 1;
}
return *this;
}
ModInt operator-() const { return ModInt(-x); }
ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
ModInt operator^(const int64_t n) const { return ModInt(*this) ^= n; }
bool operator==(const ModInt &p) const { return x == p.x; }
bool operator!=(const ModInt &p) const { return x != p.x; }
ModInt inverse() const {
int a = x, b = mod, u = 1, v = 0, t;
while(b > 0) {
t = a / b;
a -= t * b;
swap(a, b);
u -= t * v;
swap(u, v);
}
return ModInt(u);
}
friend ostream &operator<<(ostream &os, const ModInt< mod > &p) {
return os << p.x;
}
friend istream &operator>>(istream &is, ModInt< mod > &a) {
int64_t t;
is >> t;
a = ModInt< mod >(t);
return (is);
}
};
using modint = ModInt< mod >;
template< typename T >
struct Combination {
vector< T > _fact, _rfact;
Combination(int sz) : _fact(sz + 1), _rfact(sz + 1) {
_fact[0] = _rfact[sz] = 1;
for(int i = 1; i <= sz; i++) _fact[i] = _fact[i - 1] * i;
_rfact[sz] /= _fact[sz];
for(int i = sz - 1; i >= 0; i--) _rfact[i] = _rfact[i + 1] * (i + 1);
}
inline T fact(int k) const { return _fact[k]; }
inline T rfact(int k) const { return _rfact[k]; }
T P(int n, int r) const {
if(r < 0 || n < r) return 0;
return fact(n) * rfact(n - r);
}
T C(int p, int q) const {
if(q < 0 || p < q) return 0;
return fact(p) * rfact(q) * rfact(p - q);
}
T H(int n, int r) const {
if(n < 0 || r < 0) return (0);
return r == 0 ? 1 : C(n + r - 1, r);
}
};
int main() {
int N, K;
cin >> N >> K;
Combination< modint > comb(N);
//
modint ret;
for(int idx = 1; idx <= N; idx++) {
ret += comb.P(N - 1, K) * idx;
if(idx != N) ret += comb.C(K, 2) * comb.P(N - 2, K - 2) * idx;
}
cout << ret << endl;
}
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