結果

問題 No.834 Random Walk Trip
コンテスト
ユーザー rniya
提出日時 2020-10-06 00:23:30
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 5,898 bytes
コンパイル時間 1,808 ms
コンパイル使用メモリ 196,956 KB
最終ジャッジ日時 2025-01-15 02:58:53
ジャッジサーバーID
（参考情報） 		judge2 / judge1
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ファイルパターン 結果
other AC * 13 WA * 13
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ソースコード

diff # 

#include <bits/stdc++.h>
using namespace std;
#define LOCAL
#pragma region Macros
typedef long long ll;
#define ALL(x) (x).begin(),(x).end()
const long long MOD=1000000007;
// const long long MOD=998244353;
const int INF=1e9;
const long long IINF=1e18;
const int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
const char dir[4]={'D','R','U','L'};

template<typename T>
istream &operator>>(istream &is,vector<T> &v){
    for (T &x:v) is >> x;
    return is;
}
template<typename T>
ostream &operator<<(ostream &os,const vector<T> &v){
    for (int i=0;i<v.size();++i){
        os << v[i] << (i+1==v.size()?"": " ");
    }
    return os;
}
template<typename T,typename U>
ostream &operator<<(ostream &os,const pair<T,U> &p){
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template<typename T,typename U>
ostream &operator<<(ostream &os,const map<T,U> &m){
    os << '{';
    for (auto itr=m.begin();itr!=m.end();++itr){
        os << '(' << itr->first << ',' << itr->second << ')';
        if (++itr!=m.end()) os << ',';
        --itr;
    }
    os << '}';
    return os;
}
template<typename T>
ostream &operator<<(ostream &os,const set<T> &s){
    os << '{';
    for (auto itr=s.begin();itr!=s.end();++itr){
        os << *itr;
        if (++itr!=s.end()) os << ',';
        --itr;
    }
    os << '}';
    return os;
}

void debug_out(){cerr << '\n';}
template<class Head,class... Tail>
void debug_out(Head&& head,Tail&&... tail){
    cerr << head;
    if (sizeof...(Tail)>0) cerr << ", ";
    debug_out(move(tail)...);
}
#ifdef LOCAL
#define debug(...) cerr << " ";\
cerr << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]" << '\n';\
cerr << " ";\
debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

template<typename T> T gcd(T x,T y){return y!=0?gcd(y,x%y):x;}
template<typename T> T lcm(T x,T y){return x/gcd(x,y)*y;}

template<class T1,class T2> inline bool chmin(T1 &a,T2 b){
    if (a>b){a=b; return true;} return false;
}
template<class T1,class T2> inline bool chmax(T1 &a,T2 b){
    if (a<b){a=b; return true;} return false;
}
#pragma endregion

template<uint32_t mod> class modint{
    using i64=int64_t;
    using u32=uint32_t;
    using u64=uint64_t;
public:
    u32 v;
    constexpr modint(const i64 x=0) noexcept :v(x<0?mod-1-(-(x+1)%mod):x%mod){}
    constexpr u32 &value() noexcept {return v;}
    constexpr const u32 &value() const noexcept {return v;}
    constexpr modint operator+(const modint &rhs) const noexcept {return modint(*this)+=rhs;}
    constexpr modint operator-(const modint &rhs) const noexcept {return modint(*this)-=rhs;}
    constexpr modint operator*(const modint &rhs) const noexcept {return modint(*this)*=rhs;}
    constexpr modint operator/(const modint &rhs) const noexcept {return modint(*this)/=rhs;}
    constexpr modint &operator+=(const modint &rhs) noexcept {
        v+=rhs.v;
        if (v>=mod) v-=mod;
        return *this;
    }
    constexpr modint &operator-=(const modint &rhs) noexcept {
        if (v<rhs.v) v+=mod;
        v-=rhs.v;
        return *this;
    }
    constexpr modint &operator*=(const modint &rhs) noexcept {
        v=(u64)v*rhs.v%mod;
        return *this;
    }
    constexpr modint &operator/=(const modint &rhs) noexcept {
        return *this*=rhs.pow(mod-2);
    }
    constexpr modint pow(u64 exp) const noexcept {
        modint self(*this),res(1);
        while (exp>0){
            if (exp&1) res*=self;
            self*=self; exp>>=1;
        }
        return res;
    }
    constexpr modint &operator++() noexcept {if (++v==mod) v=0; return *this;}
    constexpr modint &operator--() noexcept {if (v==0) v=mod; return --v,*this;}
    constexpr modint operator++(int) noexcept {modint t=*this; return ++*this,t;}
    constexpr modint operator--(int) noexcept {modint t=*this; return --*this,t;}
    template<class T> friend constexpr modint operator+(T x,modint y) noexcept {return modint(x)+y;}
    template<class T> friend constexpr modint operator-(T x,modint y) noexcept {return modint(x)-y;}
    template<class T> friend constexpr modint operator*(T x,modint y) noexcept {return modint(x)*y;}
    template<class T> friend constexpr modint operator/(T x,modint y) noexcept {return modint(x)/y;}
    constexpr bool operator==(const modint &rhs) const noexcept {return v==rhs.v;}
    constexpr bool operator!=(const modint &rhs) const noexcept {return v!=rhs.v;}
    constexpr bool operator!() const noexcept {return !v;}
    friend istream &operator>>(istream &s,modint &rhs) noexcept {
        i64 v; rhs=modint{(s>>v,v)}; return s;
    }
    friend ostream &operator<<(ostream &s,const modint &rhs) noexcept {
        return s<<rhs.v;
    }
};

template<class M>
struct Combination{
    vector<M> _fac,_inv,_finv;
    Combination(int n):_fac(n+1),_inv(n+1),_finv(n+1){
        _fac[0]=_finv[n]=_inv[0]=1;
        for (int i=1;i<=n;++i) _fac[i]=_fac[i-1]*i;
        _finv[n]/=_fac[n];
        for (int i=n-1;i>=0;--i) _finv[i]=_finv[i+1]*(i+1);
        for (int i=1;i<=n;++i) _inv[i]=_finv[i]*_fac[i-1];
    }
    M fac(int k) const {return _fac[k];}
    M finv(int k) const {return _finv[k];}
    M inv(int k) const {return _inv[k];}
    M P(int n,int r) const {
        if (n<0||r<0||n<r) return 0;
        return _fac[n]*_finv[n-r];
    }
    M C(int n,int r) const {
        if (n<0||r<0||n<r) return 0;
        return _fac[n]*_finv[r]*_finv[n-r];
    }
};

using mint=modint<MOD>;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    Combination<mint> COM(1000010);
    int N,M; cin >> N >> M;
    if (N==1){cout << 1 << '\n'; return 0;}

    mint ans=0;
    for (int i=0;i<=M;++i){
        if (i%(2*N)==2*N-1&&(i+M)%2==0) ans+=COM.C(M,(i+M)/2);
        if (i%(2*N)==0&&(i+M)%2==0) ans+=COM.C(M,(i+M)/2);
        if (i%(2*N)==0&&(M-i)%2==0) ans+=COM.C(M,(M-i)/2);
        if (i%(2*N)==1&&(M-i)%2==0) ans+=COM.C(M,(M-i)/2);
    }

    cout << ans << '\n';
}
0