Submission #74308638

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Source Code Expand

#include<bits/extc++.h>

#pragma GCC optimize("O3","unroll-loops")
#pragma GCC target("avx,avx2")

#include<iostream>
#include<queue>
#include<vector>
#include<cmath>
#include<map>

using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;

#define coutc "\033[48;5;196m\033[38;5;15m"
#define endc "\033[0m"
#define M(_1, _2, _3, _4, NAME, ...) NAME
#define rep(...) \
  M(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rep4(_, x, n, s) \
  for (int _ = x; (s < 0) ? _ > n : _ < n; _ += s)
#define rep3(_, x, n) rep4(_, x, n, (x < n ? 1 : -1))
#define rep2(_, n) rep3(_, 0, n)
#define rep1(n) rep2(i, n)

#define FOR(i, a, b) for (int i=a; i<b; i++)
#define F0R(i, a) for (int i=0; i<a; i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define gcd(a,b) __gcd(a,b)
#define lcm(a,b) a*b/gcd(a,b)

#define mp make_pair
// #define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define endl "\n"

// #define cin fin
// #define cout fout

// ifstream fin("word.in");
// ofstream fout("word.out");

const int inf = INT_MAX;
const int MOD = 998244353;
double PI = 4*atan(1);

#ifdef DEBUG
string to_string(char c) { return string({c}); }
// 7
template<class... Ts>
ostream& operator<<(ostream& o, tuple<Ts...> t) {
  string s = "(";
  apply([&](auto&&... r) {
    ((s += to_string(r) + ", "), ...); }, t);
  return o << s.substr(0, len(s) - 2) + ")";
}
// 3
ostream& operator<<(ostream &o, pair<auto, auto> p) {
  return o << "(" << p.fi << ", " << p.se << ")";
}
// 7
template<class C, class T = typename C::value_type,
typename std::enable_if<!std::is_same<C, std::string>
::value>::type* = nullptr>
ostream& operator<<(ostream &o, C c) {
  for (auto e : c) o << setw(7) << right << e;
  return o << endc << endl << coutc;
}
// 7
void debug(const auto &e, const auto &... r) {
  cout << coutc << e;
  ((cout << " " << r), ..., (cout << endc << endl));
}
#else
#define debug(...)
#endif

map<string,int> mon;
map<int,string> inp;

ll pw(ll a, ll e) {
    ll r = 1;
    while (e) {
        if (e & 1) r = r * a % MOD;
        a = a * a % MOD;
        e >>= 1;
    }
    return r;
}

void _main(int tc) {
    int N;
    cin >> N;

    ll s = 0, q = 0;
    int i = 0;
    while (i < N) {
        ll x;
        cin >> x;
        x %= MOD;
        s += x;
        if (s >= MOD) s -= MOD;
        q += x * x % MOD;
        if (q >= MOD) q -= MOD;
        i++;
    }

    if (N == 1) {
        cout << q << endl;
        return;
    }

    if (N == 2) {
        ll ans = (s * s % MOD - 2 * q % MOD + MOD) % MOD;
        ans = (q + ans) % MOD;
        cout << ans << endl;
        return;
    }

    ll num = ((3LL * N - 1) % MOD) * q % MOD;
    num = (num - 2 * s % MOD * s % MOD + MOD) % MOD;

    ll den = 3LL * (N - 1) % MOD;
    ll ans = num * pw(den, MOD - 2) % MOD;

    cout << ans << endl;
}
// 5
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  _main(0), exit(0);
  int tc; cin >> tc; rep(i, tc) _main(i + 1);
}

Submission Info

Compile Error

./Main.cpp: In function 'void _main(int)':
./Main.cpp:102:16: warning: unused parameter 'tc' [-Wunused-parameter]
  102 | void _main(int tc) {
      |            ~~~~^~

Judge Result