結果

問題 No.2327 Inversion Sum
ユーザー sten_san
提出日時 2023-05-28 14:40:36
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 31 ms / 2,000 ms
コード長 4,059 bytes
コンパイル時間 2,108 ms
コンパイル使用メモリ 211,840 KB
最終ジャッジ日時 2025-02-13 11:52:08
ジャッジサーバーID
(参考情報)
judge3 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 30
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#include <bits/stdc++.h>
using namespace std;
struct iofast_t {
iofast_t() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
}
} iofast;
struct uns_t {} uns;
template <typename Element, typename Head, typename ...Args>
auto vec(Element init, Head arg, Args ...args) {
if constexpr (sizeof...(Args) == 0) return vector(arg, init);
else return vector(arg, vec(init, args...));
}
template <typename Element, typename Head, typename ...Args>
auto vec(uns_t, Head arg, Args ...args) {
return vec(Element(), arg, args...);
}
template <typename Container>
auto distance(const Container &c, decltype(begin(c)) iter) {
return distance(begin(c), iter);
}
template <typename RIter, typename Compare = less<typename iterator_traits<RIter>::value_type>>
auto isort(RIter first, RIter last, Compare comp = Compare()) {
vector<int> i(distance(first, last));
iota(begin(i), end(i), 0);
sort(begin(i), end(i), [&](auto x, auto y) {
return comp(*(first + x), *(first + y));
});
return i;
}
template <typename, template <typename> typename, typename = void_t<>>
struct detect : false_type {};
template <typename T, template <typename> typename Check>
struct detect<T, Check, void_t<Check<T>>> : true_type {};
template <typename T, template <typename> typename Check>
constexpr inline bool detect_v = detect<T, Check>::value;
template <typename T>
using has_member_sort = decltype(declval<T>().sort());
template <typename Container, typename Compare = less<typename Container::value_type>>
auto sorted(Container c, Compare comp = Compare()) {
if constexpr (detect_v<Container, has_member_sort>) {
c.sort(comp);
return c;
}
else {
sort(begin(c), end(c), comp);
return c;
}
}
template <typename Container, typename Compare = equal_to<typename Container::value_type>>
auto uniqued(Container c, Compare comp = Compare()) {
c.erase(unique(begin(c), end(c), comp), end(c));
return c;
}
template <typename T, typename Compare = less<T>>
T &chmin(T &l, T r, Compare &&f = less<T>()) { return l = min(l, r, f); }
template <typename T, typename Compare = less<T>>
T &chmax(T &l, T r, Compare &&f = less<T>()) { return l = max(l, r, f); }
template <typename F>
constexpr auto fix(F &&f) noexcept {
return [f = std::tuple<F>(std::forward<F>(f))](auto &&...args) mutable {
return std::get<0>(f)(fix(std::get<0>(f)), std::forward<decltype(args)>(args)...);
};
}
#include <atcoder/segtree>
int op(int x, int y) {
return x + y;
}
int elem() {
return 0;
}
using segtree = atcoder::segtree<int, op, elem>;
#include <atcoder/modint>
using mint = atcoder::modint998244353;
int main() {
int n, m; cin >> n >> m;
auto l = vec<array<int, 2>>(uns, m);
for (auto &[p, k] : l) {
cin >> p >> k; --p; --k;
}
sort(begin(l), end(l), [](auto x, auto y) {
return x[1] < y[1];
});
auto f = vec<mint>(uns, n + 1);
f[0] = 1;
for (int i = 1; i <= n; ++i) {
f[i] = f[i - 1] * i;
}
mint ans = [&]() {
mint sum = 0;
segtree seg(n);
for (auto [p, k] : l) {
sum += seg.prod(p, n);
seg.set(p, 1);
}
return sum * f[n - m];
}();
auto used = vec<char>(false, n);
for (auto [p, k] : l) {
used[p] = true;
}
segtree unused(n);
for (int i = 0; i < n; ++i) {
if (!used[i]) {
unused.set(i, 1);
}
}
int used1 = 0;
for (auto [p, k] : l) {
mint rem = k - used1++;
mint upper = unused.prod(p, n);
ans += upper * rem * f[max(0, n - m - 1)];
}
reverse(begin(l), end(l));
int used2 = 0;
for (auto [p, k] : l) {
mint rem = (n - k - 1) - used2++;
mint lower = unused.prod(0, p);
ans += lower * rem * f[max(0, n - m - 1)];
}
mint count = n - m;
ans += (count * (count - 1) / 2) * f[max(0, n - m - 2)] * (mint(max(1, n - m)) * max(0, n - m - 1) / 2);
cout << ans.val() << endl;
}
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