結果

問題 No.1785 Inequality Signs
ユーザー milanis48663220milanis48663220
提出日時 2021-12-29 19:47:19
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 258 ms / 2,000 ms
コード長 4,097 bytes
コンパイル時間 1,204 ms
コンパイル使用メモリ 115,920 KB
最終ジャッジ日時 2025-01-27 07:29:33
ジャッジサーバーID
(参考情報)
judge4 / judge5
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 52
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <tuple>
#include <cmath>
#include <numeric>
#include <functional>
#include <cassert>
#define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl;
#define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
using namespace std;
typedef long long ll;
template<typename T>
vector<vector<T>> vec2d(int n, int m, T v){
return vector<vector<T>>(n, vector<T>(m, v));
}
template<typename T>
vector<vector<vector<T>>> vec3d(int n, int m, int k, T v){
return vector<vector<vector<T>>>(n, vector<vector<T>>(m, vector<T>(k, v)));
}
template<typename T>
void print_vector(vector<T> v, char delimiter=' '){
if(v.empty()) {
cout << endl;
return;
}
for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter;
cout << v.back() << endl;
}
const ll MOD = 1000000007;
class ModInt{
public:
ll v;
ModInt(ll _v = 0){
if(_v < 0) _v = (_v%MOD)+MOD;
if(_v >= MOD) _v %= MOD;
v = _v;
}
ModInt operator+(ll n){
return ModInt((v+n)%MOD);
}
ModInt operator-(ll n){
return ModInt((v-n+MOD)%MOD);
}
ModInt operator*(ll n){
if(n >= MOD) n %= MOD;
return ModInt((v*n)%MOD);
}
ModInt operator/(ll n){
return ModInt((ModInt(n).inv()*v).v%MOD);
}
ModInt &operator+=(ll n){
v = (v+n)%MOD;
return *this;
}
ModInt &operator-=(ll n){
v = (v-n+MOD)%MOD;
return *this;
}
ModInt &operator*=(ll n){
v = (v*n+MOD)%MOD;
return *this;
}
ModInt operator+(ModInt n){
return ModInt((v+n.v)%MOD);
}
ModInt operator-(ModInt n){
return ModInt((v-n.v+MOD)%MOD);
}
ModInt operator*(ModInt n){
return ModInt((v*n.v)%MOD);
}
ModInt operator/(ModInt n){
return ModInt((n.inv()*v).v%MOD);
}
ModInt &operator+=(ModInt n){
v = (v+n.v)%MOD;
return *this;
}
ModInt &operator-=(ModInt n){
v = (v-n.v+MOD)%MOD;
return *this;
}
ModInt &operator*=(ModInt n){
v = (v*n.v)%MOD;
return *this;
}
bool operator==(ModInt n){
return v == n.v;
}
bool operator!=(ModInt n){
return v != n.v;
}
ModInt &operator=(ll n){
v = n%MOD;
return *this;
}
ModInt inv(){
if(v == 1) return ModInt(1);
else return ModInt(MOD-ModInt(MOD%v).inv().v*(MOD/v)%MOD);
}
};
ostream& operator<<(ostream& os, const ModInt& m){
os << m.v;
return os;
}
istream & operator >> (istream &in, ModInt &m){
in >> m.v;
return in;
}
ModInt pow(ModInt a, ll n) {
assert(n >= 0);
ModInt ans = 1;
while (n > 0) {
if (n&1) ans = ans*a;
a = a*a;
n >>= 1;
}
return ans;
}
#define N_MAX 200002
ModInt inv[N_MAX],fac[N_MAX],finv[N_MAX];
void init(){
fac[0]=1;fac[1]=1;
finv[0]=1;finv[1]=1;
inv[1]=1;
for(int i=2;i<N_MAX;i++){
inv[i]=ModInt(MOD)-inv[MOD%i]*(MOD/i);
fac[i]=fac[i-1]*(ll) i;
finv[i]=finv[i-1]*inv[i];
}
}
ModInt comb(ll n, ll r){
if(n < r){
return ModInt(0);
}else{
return fac[n]*finv[r]*finv[n-r];
}
}
using mint = ModInt;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout << setprecision(10) << fixed;
init();
int n, k; cin >> n >> k;
mint ans = 0;
mint num = 1;
for(int i = k; i < k+n; i++) num *= i;
for(int i = 0; i <= n-1; i++){
int rem = k-1-i;
if(rem < 0) break;
if(i > 0){
num *= mint(k-i+n).inv();
num *= k-i;
}
ans += comb(n-1, i)*num/fac[n];
}
cout << ans << endl;
}
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