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E.cpp
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50 lines (38 loc) · 1.22 KB
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#include <bits/stdc++.h>
#include <atcoder/modint>
#include <atcoder/fenwicktree>
using namespace std;
using ll = long long;
using ld = long double;
#define rep(i, a, b) for (auto i = (a); i < (b); ++i)
#define per(i, a, b) for (auto i = (b); i-- > (a); )
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) int((x).size())
template<class T> bool uin(T& a, const T& b) { return a > b ? a = b, true : false; }
template<class T> bool uax(T& a, const T& b) { return a < b ? a = b, true : false; }
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
using mint = atcoder::modint998244353;
const mint two = mint::raw(2), half = 1 / mint::raw(2);
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n; cin >> n;
vector<int> a(n);
for (auto &x : a)
cin >> x;
auto cmp = a;
sort(all(cmp)); cmp.erase(unique(all(cmp)), end(cmp));
for (auto &x : a)
x = lower_bound(all(cmp), x) - begin(cmp);
atcoder::fenwick_tree<mint> t(n);
mint x = two.pow(n), p = half.pow(n);
mint ans = 0;
for (int i = 0; i < n; ++i) {
ans += t.sum(0, a[i] + 1) * p;
p *= two;
x *= half;
t.add(a[i], x);
}
cout << ans.val() << '\n';
}