結果

問題 No.1300 Sum of Inversions
ユーザー 👑 emthrmemthrm
提出日時 2020-11-27 21:44:48
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 218 ms / 2,000 ms
コード長 6,088 bytes
コンパイル時間 2,373 ms
コンパイル使用メモリ 206,608 KB
最終ジャッジ日時 2025-01-16 06:51:26
ジャッジサーバーID
(参考情報)
judge4 / judge5
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ファイルパターン 結果
sample AC * 3
other AC * 34
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ソースコード

diff #
プレゼンテーションモードにする

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
IOSetup() {
std::cin.tie(nullptr);
std::ios_base::sync_with_stdio(false);
std::cout << fixed << setprecision(20);
}
} iosetup;
template <int MOD>
struct MInt {
unsigned val;
MInt(): val(0) {}
MInt(long long x) : val(x >= 0 ? x % MOD : x % MOD + MOD) {}
static int get_mod() { return MOD; }
static void set_mod(int divisor) { assert(divisor == MOD); }
MInt pow(long long exponent) const {
MInt tmp = *this, res = 1;
while (exponent > 0) {
if (exponent & 1) res *= tmp;
tmp *= tmp;
exponent >>= 1;
}
return res;
}
MInt &operator+=(const MInt &x) { if((val += x.val) >= MOD) val -= MOD; return *this; }
MInt &operator-=(const MInt &x) { if((val += MOD - x.val) >= MOD) val -= MOD; return *this; }
MInt &operator*=(const MInt &x) { val = static_cast<unsigned long long>(val) * x.val % MOD; return *this; }
MInt &operator/=(const MInt &x) {
// assert(std::__gcd(static_cast<int>(x.val), MOD) == 1);
unsigned a = x.val, b = MOD; int u = 1, v = 0;
while (b) {
unsigned tmp = a / b;
std::swap(a -= tmp * b, b);
std::swap(u -= tmp * v, v);
}
return *this *= u;
}
bool operator==(const MInt &x) const { return val == x.val; }
bool operator!=(const MInt &x) const { return val != x.val; }
bool operator<(const MInt &x) const { return val < x.val; }
bool operator<=(const MInt &x) const { return val <= x.val; }
bool operator>(const MInt &x) const { return val > x.val; }
bool operator>=(const MInt &x) const { return val >= x.val; }
MInt &operator++() { if (++val == MOD) val = 0; return *this; }
MInt operator++(int) { MInt res = *this; ++*this; return res; }
MInt &operator--() { val = (val == 0 ? MOD : val) - 1; return *this; }
MInt operator--(int) { MInt res = *this; --*this; return res; }
MInt operator+() const { return *this; }
MInt operator-() const { return MInt(val ? MOD - val : 0); }
MInt operator+(const MInt &x) const { return MInt(*this) += x; }
MInt operator-(const MInt &x) const { return MInt(*this) -= x; }
MInt operator*(const MInt &x) const { return MInt(*this) *= x; }
MInt operator/(const MInt &x) const { return MInt(*this) /= x; }
friend std::ostream &operator<<(std::ostream &os, const MInt &x) { return os << x.val; }
friend std::istream &operator>>(std::istream &is, MInt &x) { long long val; is >> val; x = MInt(val); return is; }
};
namespace std { template <int MOD> MInt<MOD> abs(const MInt<MOD> &x) { return x; } }
template <int MOD>
struct Combinatorics {
using ModInt = MInt<MOD>;
int val; // "val!" and "mod" must be disjoint.
std::vector<ModInt> fact, fact_inv, inv;
Combinatorics(int val = 10000000) : val(val), fact(val + 1), fact_inv(val + 1), inv(val + 1) {
fact[0] = 1;
for (int i = 1; i <= val; ++i) fact[i] = fact[i - 1] * i;
fact_inv[val] = ModInt(1) / fact[val];
for (int i = val; i > 0; --i) fact_inv[i - 1] = fact_inv[i] * i;
for (int i = 1; i <= val; ++i) inv[i] = fact[i - 1] * fact_inv[i];
}
ModInt nCk(int n, int k) const {
if (n < 0 || n < k || k < 0) return 0;
assert(n <= val && k <= val);
return fact[n] * fact_inv[k] * fact_inv[n - k];
}
ModInt nPk(int n, int k) const {
if (n < 0 || n < k || k < 0) return 0;
assert(n <= val);
return fact[n] * fact_inv[n - k];
}
ModInt nHk(int n, int k) const {
if (n < 0 || k < 0) return 0;
return k == 0 ? 1 : nCk(n + k - 1, k);
}
};
using ModInt = MInt<MOD>;
template <typename Abelian>
struct BIT {
BIT(int n, const Abelian UNITY = 0) : n(n), UNITY(UNITY), dat(n, UNITY) {}
void add(int idx, Abelian val) {
while (idx < n) {
dat[idx] += val;
idx |= idx + 1;
}
}
Abelian sum(int idx) const {
Abelian res = UNITY;
--idx;
while (idx >= 0) {
res += dat[idx];
idx = (idx & (idx + 1)) - 1;
}
return res;
}
Abelian sum(int left, int right) const {
return left < right ? sum(right) - sum(left) : UNITY;
}
Abelian operator[](const int idx) const { return sum(idx, idx + 1); }
int lower_bound(Abelian val) const {
if (val <= UNITY) return 0;
int res = 0, exponent = 1;
while (exponent <= n) exponent <<= 1;
for (int mask = exponent >> 1; mask > 0; mask >>= 1) {
if (res + mask - 1 < n && dat[res + mask - 1] < val) {
val -= dat[res + mask - 1];
res += mask;
}
}
return res;
}
private:
int n;
const Abelian UNITY;
std::vector<Abelian> dat;
};
int main() {
int n; cin >> n;
vector<int> a(n); REP(i, n) cin >> a[i];
vector<int> b(a);
sort(ALL(b));
b.erase(unique(ALL(b)), b.end());
int m = b.size();
BIT<ModInt> bit1(m), bit3(m), bit4(m);
BIT<int> bit2(m);
REP(i, n) {
int idx = lower_bound(ALL(b), a[i]) - b.begin();
bit3.add(idx, bit1.sum(idx + 1, m));
int cnt = bit2.sum(idx + 1, m);
bit3.add(idx, 1LL * a[i] * cnt);
bit4.add(idx, cnt);
bit1.add(idx, a[i]);
bit2.add(idx, 1);
}
ModInt ans = 0;
for (int i = n - 1; i >= 0; --i) {
int idx = lower_bound(ALL(b), a[i]) - b.begin();
bit1.add(idx, -a[i]);
bit2.add(idx, -1);
bit3.add(idx, -bit1.sum(idx + 1, m));
int cnt = bit2.sum(idx + 1, m);
bit3.add(idx, -1LL * a[i] * cnt);
bit4.add(idx, -cnt);
ans += bit3.sum(idx + 1, m) + bit4.sum(idx + 1, m) * a[i];
}
cout << ans << '\n';
return 0;
}
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