Submission #3261403

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<int(n);++i)
typedef long long ll;

class modint {
  public:
    using ll = long long;
    ll num;
    static const ll MOD = 1e9+7;
    static vector<modint> factorial;

    modint(): num(0) {};
    modint(ll _n): num((_n + MOD) % MOD) {}
    modint(const modint &r): num(r.num) {}
    operator ll() const { return (num+MOD)%MOD; }
    friend istream& operator>>(istream& is, modint &r){
        ll num_;
        is >> num_;
        r = num_;
        return is;
    }
    modint operator+(const modint &r) const { return modint(num + r.num); }
    modint operator-(const modint &r) const { return modint(num - r.num); }
    modint operator*(const modint &r) const { return modint(num * r.num); }

    template<typename T>
    modint operator^(const T &r) const {
        if(r == 0) return 1;
        return (((*this)*(*this)) ^ (r/2)) * modint(r&1 ? num : 1);
    }
    modint operator/(const modint &r) const { return num * (r^(MOD-2)); }

    modint operator+=(const modint &r) { return *this = *this + r; }
    modint operator-=(const modint &r) { return *this = *this - r; }
    modint operator*=(const modint &r) { return *this = *this * r; }
    modint operator/=(const modint &r) { return *this = *this / r; }

    template<typename T>
    modint operator^=(const T &r) { return *this = *this ^ r; }

    static modint fact(int n){
        if((int)factorial.size() <= n) factorial.resize(n+1);
        if(factorial[n]) return factorial[n];
        if(n == 0) return 1;
        return factorial[n] = modint(n) * fact(n-1);
    }

    static modint com(ll n,ll r){
        return n >= r ? fact(n)/(fact(n-r)*fact(r)) : modint(0);
    }
};
vector<modint> modint::factorial;


modint solve(vector<ll> &v,int n){
    modint sum = 0;
    rep(i,n-1) sum += modint(v[i+1]-v[i]) * modint((i+1) * (n-i-1));
    return sum;
}

int main(void){
    int n,m;
    cin>>n>>m;
    vector<ll> x(n),y(m);
    rep(i,n) cin>>x[i];
    rep(i,m) cin>>y[i];
    cout<<solve(x,n) * solve(y,m)<<endl;
    return 0;
}

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