結果
問題 | No.1300 Sum of Inversions |
ユーザー |
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提出日時 | 2020-11-27 21:31:44 |
言語 | C++17 (gcc 13.3.0 + boost 1.87.0) |
結果 |
AC
|
実行時間 | 384 ms / 2,000 ms |
コード長 | 4,439 bytes |
コンパイル時間 | 2,710 ms |
コンパイル使用メモリ | 211,768 KB |
最終ジャッジ日時 | 2025-01-16 06:34:11 |
ジャッジサーバーID (参考情報) |
judge3 / judge3 |
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ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 34 |
ソースコード
#include <bits/stdc++.h>using namespace std;template <int mod = (int)(998244353)>struct ModInt {int x;ModInt() : x(0) {}ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}ModInt &operator+=(const ModInt &p) {if ((x += p.x) >= mod) x -= mod;return *this;}ModInt &operator-=(const ModInt &p) {if ((x += mod - p.x) >= mod) x -= mod;return *this;}ModInt &operator*=(const ModInt &p) {x = (int)(1LL * x * p.x % mod);return *this;}ModInt &operator/=(const ModInt &p) {*this *= p.inverse();return *this;}ModInt operator-() const { return ModInt(-x); }ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }bool operator==(const ModInt &p) const { return x == p.x; }bool operator!=(const ModInt &p) const { return x != p.x; }ModInt inverse() const {int a = x, b = mod, u = 1, v = 0, t;while (b > 0) {t = a / b;swap(a -= t * b, b);swap(u -= t * v, v);}return ModInt(u);}ModInt pow(int64_t n) const {ModInt res(1), mul(x);while (n) {if (n & 1) res *= mul;mul *= mul;n >>= 1;}return res;}friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; }friend istream &operator>>(istream &is, ModInt &a) {int64_t t;is >> t;a = ModInt<mod>(t);return (is);}static int get_mod() { return mod; }};struct Combination {vector<ModInt<>> _fact, _rfact, _inv;Combination(long long nsize = 5000000): _fact(nsize + 1), _rfact(nsize + 1), _inv(nsize + 1) {_fact[0] = _rfact[nsize] = _inv[0] = 1;for (int i = 1; i <= nsize; i++) _fact[i] = _fact[i - 1] * i;_rfact[nsize] /= _fact[nsize];for (int i = nsize - 1; i >= 0; i--) _rfact[i] = _rfact[i + 1] * (i + 1);for (int i = 1; i <= nsize; i++) _inv[i] = _rfact[i] * _fact[i - 1];}inline ModInt<> fact(int k) const { return _fact[k]; }inline ModInt<> rfact(int k) const { return _rfact[k]; }inline ModInt<> inv(int k) const { return _inv[k]; }ModInt<> P(int n, int r) const {if (r < 0 || n < r) return 0;return fact(n) * rfact(n - r);}ModInt<> C(int p, int q) const {if (q < 0 || p < q) return 0;return fact(p) * rfact(q) * rfact(p - q);}ModInt<> largeC(long long p, long long q) const {if (q < 0 || p < q) return 0;ModInt<> res = rfact(q);for (int i = 0; i < q; ++i) res *= p - i;return res;}// n types,choose rModInt<> H(int n, int r) const {if (n < 0 || r < 0) return (0);return r == 0 ? 1 : C(n + r - 1, r);}ModInt<> Catalan(int n) {// C(2n,n) / (n + 1)return fact(2 * n) * rfact(n + 1) * rfact(n);}};using mint = ModInt<>;// 0-indexedtemplate <class T>struct BIT {int treesize;vector<T> lst;// constructorBIT(int newn = 0) : treesize(newn), lst(newn + 1, 0) {}// a_place += numvoid add(int place, T num) {++place;while (place <= treesize) {lst[place] += num;place += place & -place;}}// sum between [0,place)T sum(int place) {T res = 0;while (place > 0) {res += lst[place];place -= place & -place;}return res;}// sum [l,r)T sum(int left, int right) { return sum(right) - sum(left); }};int n;BIT<mint> sum[2], cnt[2];vector<long long> a;map<long long, int> id;mint solve();int main() {cin >> n;a.resize(n);for (auto &p : a) cin >> p;{vector<long long> v;for (int i = 0; i < n; ++i) v.push_back(a[i]);sort(v.begin(), v.end());v.erase(unique(v.begin(), v.end()), v.end());int len = v.size();for (int i = 0; i < len; ++i) id[v[i]] = i;}cout << solve() << endl;return 0;}mint solve() {int len = id.size();mint res;sum[0] = cnt[0] = sum[1] = cnt[1] = BIT<mint>(n);for (int i = 0; i < n; ++i) {int nid = id[a[i]];mint nsum = sum[0].sum(nid + 1, len), ncnt = cnt[0].sum(nid + 1, len);res += sum[1].sum(nid + 1, len) + cnt[1].sum(nid + 1, len) * a[i];sum[1].add(nid, nsum + ncnt * a[i]);cnt[1].add(nid, ncnt);sum[0].add(nid, a[i]);cnt[0].add(nid, 1);}return res;}