Source Code
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define fixed(n) cout << fixed << setprecision(n);
#define mod 1000000007
#define cin(v) for (auto&i:v) cin >> i;
#define cout(v) for (auto&i:v) cout << i << " ";
#define ceil(n,m) (n / m + (n%m != 0))
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()

void lil_codi_vert(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
    #endif
}

//int dx[] = {1, 1, 1, 0, 0, -1, -1, -1};
//int dy[] = {-1, 0, 1, -1, 1, -1, 0, 1};


// fast power
ll fastpow(ll b, ll e){
    ll res = 1;
    while(e){
        if(e&1) res = ((res%mod) * (b%mod)) % mod;
        e /= 2;
        b = ((b%mod) * (b%mod)) % mod;
    }
    return res % mod;
}


// mod inverse
ll inverse(ll n){
    return fastpow(n, mod - 2);
}

int main(){
    lil_codi_vert();
    ll n; 
    vector<ll> start, en;
    cin >> n;
    start.resize(n); cin(start);
    en.resize(n); cin(en);

    vector<ll> fact(200005, 0);
    fact[0] = 1;
    for(ll i = 1; i <= 200005; i++){
        fact[i] = (fact[i-1] %mod) * (i % mod);
        fact[i] %= mod;
    }


    vector<ll> res(n);
    for(int i = 0; i < n ; i++){
        res[i] = max(0ll, en[i] - start[i] - 1);
    }
    //cout(res);

    ll sum = 0;
    for(auto&i: res){
        sum += i;
    }

    ll ub = 0;
    if(sum <= 2e5) ub = fact[sum];
    else{
        ub = 1;
        for(int i = 1 ; i <= sum; i++){
            ub = (ub %mod) * (i %mod);
            ub %= mod;
        }
    }
    //cout << ub;
    ll down = 1;
    for(auto&i: res){
        down = (down % mod) * (fact[i]  % mod);
        down %= mod;
    }

    cout << ((ub%mod) * inverse(down)) % mod;

    return 0;
}
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N-dimensions aboelsoudJr
GNU G++17
3075 ms
6.5 MB
Time Limit Exceeded