Skittles

#pragma GCC optimize("O3,unroll-loops")

#include <bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef long double ld;

string to_string(string s) {
    return '"' + s + '"';
}
 
string to_string(const char* s) {
    return to_string((string) s);
}
 
string to_string(bool b) {
    return (b ? "true" : "false");
}
 
template <typename A, typename B>
string to_string(pair<A, B> p) {
    return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
 
template <typename A>
string to_string(A v) {
    bool first = true;
    string res = "{";
    for (const auto &x : v) {
        if (!first) {
            res += ", ";
        }
        first = false;
        res += to_string(x);
    }
    res += "}";
    return res;
}
 
void debug_out() {
    cerr << endl;
}
 
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << " " << to_string(H);
    debug_out(T...);
}
 
#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif

ll euclid(ll a, ll b, ll &x, ll &y) {
    if (!b) return x = 1, y = 0, a;
    ll d = euclid(b, a % b, y, x);
    return y -= a/b * x, d;
}

const ll mod = 998244353; // change to something else
struct Mod {
    ll x;
    Mod(ll xx) : x(xx) {}
    Mod operator+(Mod b) { return Mod((x + b.x) % mod); }
    Mod operator-(Mod b) { return Mod((x - b.x + mod) % mod); }
    Mod operator*(Mod b) { return Mod((x * b.x) % mod); }
    Mod operator/(Mod b) { return *this * invert(b); }
    Mod invert(Mod a) {
        ll x, y, g = euclid(a.x, mod, x, y);
        assert(g == 1); return Mod((x + mod) % mod);
    }
    Mod operator^(ll e) {
        if (!e) return Mod(1);
        Mod r = *this ^ (e / 2); r = r * r;
        return e&1 ? *this * r : r;
    }
};

void solve(){
    int n,a,b;
    cin>>n>>a>>b;
    vector<Mod> fact(2*b+1,Mod(0));
    fact[0]=Mod(1);
    for (int i = 1; i<=2*b; i++){
        fact[i]=fact[i-1]*Mod(i);
    }

    auto cnk = [&](int nn, int k){
        return fact[nn]/(fact[nn-k]*fact[k]);
    };

    Mod ans = Mod(0);
    for (int i=a;i<=b;i++){
        ans = ans + cnk(i+n-1,n-1);
    }
    cout<<ans.x;
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit); // RTE if input wrong datatype

    int t=1;
    // cin>>t;

    while(t--){
        solve();
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 17

Verdict: ACCEPTED

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 35

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: WRONG ANSWER

Test 38

Verdict: WRONG ANSWER

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: WRONG ANSWER

Test 43

Verdict: ACCEPTED

Test 44

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: WRONG ANSWER

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: WRONG ANSWER

Test 53

Verdict: WRONG ANSWER

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: ACCEPTED

Test 57

Verdict: WRONG ANSWER

Test 58

Verdict: ACCEPTED

Test 59

Verdict: ACCEPTED

Test 60

Verdict: RUNTIME ERROR

code: input/code.cpp:79: Mod Mod::invert(Mod): Assertion `g == 1' failed.

Test 61

Verdict: WRONG ANSWER

Test 62

Verdict: ACCEPTED

Test 63

Verdict: WRONG ANSWER