結果
問題 | No.823 Many Shifts Easy |
ユーザー |
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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 |
ソースコード
#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);// うくうくうく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;}