結果

問題 No.1294 マウンテン数列
ユーザー m_tsubasam_tsubasa
提出日時 2020-11-20 23:03:27
言語 C++17(gcc12)
(gcc 12.3.0 + boost 1.87.0)
結果
AC  
実行時間 1,974 ms / 2,000 ms
コード長 4,242 bytes
コンパイル時間 7,659 ms
コンパイル使用メモリ 268,560 KB
最終ジャッジ日時 2025-01-16 03:05:13
ジャッジサーバーID
(参考情報)
judge2 / judge5
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ファイルパターン 結果
other AC * 17
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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

#include <bits/stdc++.h>
using namespace std;
// 0-indexed
template <class T>
struct SegmentTree {
// a,b,c: T, e:T(unit)
// abc = (ab)c = a(bc)
// ae = ea = a
typedef function<T(T, T)> F;
int n;
F f;
T unit;
vector<T> dat;
SegmentTree(){};
SegmentTree(int newn, F f, T t) : f(f), unit(t) { init(newn); }
SegmentTree(const vector<T> &v, F f, T t) : f(f), unit(t) {
int _n = v.size();
init(v.size());
for (int i = 0; i < _n; ++i) dat[n + i] = v[i];
for (int i = n - 1; i; --i) dat[i] = f(dat[i << 1], dat[(i << 1) | 1]);
}
void init(int newn) {
n = 1;
while (n < newn) n <<= 1;
dat.assign(n << 1, unit);
}
// "go up" process
void update(int k, T newdata) {
dat[k += n] = newdata;
while (k >>= 1) {
dat[k] = f(dat[(k << 1) | 0], dat[(k << 1) | 1]);
}
}
// [a,b)
T query(int a, int b) {
T vl = unit, vr = unit;
for (int l = a + n, r = b + n; l < r; l >>= 1, r >>= 1) {
if (l & 1) vl = f(vl, dat[l++]);
if (r & 1) vr = f(dat[--r], vr);
}
return f(vl, vr);
}
};
template <int mod = (int)(998244353)>
struct ModInt {
int x;
constexpr ModInt() : x(0) {}
constexpr ModInt(int64_t y)
: x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
constexpr ModInt &operator+=(const ModInt &p) noexcept {
if ((x += p.x) >= mod) x -= mod;
return *this;
}
constexpr ModInt &operator-=(const ModInt &p) noexcept {
if ((x += mod - p.x) >= mod) x -= mod;
return *this;
}
constexpr ModInt &operator*=(const ModInt &p) noexcept {
x = (int)(1LL * x * p.x % mod);
return *this;
}
constexpr ModInt &operator/=(const ModInt &p) noexcept {
*this *= p.inverse();
return *this;
}
constexpr ModInt operator-() const { return ModInt(-x); }
constexpr ModInt operator+(const ModInt &p) const noexcept {
return ModInt(*this) += p;
}
constexpr ModInt operator-(const ModInt &p) const noexcept {
return ModInt(*this) -= p;
}
constexpr ModInt operator*(const ModInt &p) const noexcept {
return ModInt(*this) *= p;
}
constexpr ModInt operator/(const ModInt &p) const noexcept {
return ModInt(*this) /= p;
}
constexpr bool operator==(const ModInt &p) const noexcept { return x == p.x; }
constexpr bool operator!=(const ModInt &p) const noexcept { return x != p.x; }
constexpr ModInt inverse() const noexcept {
int a = x, b = mod, u = 1, v = 0, t = 0;
while (b > 0) {
t = a / b;
swap(a -= t * b, b);
swap(u -= t * v, v);
}
return ModInt(u);
}
constexpr 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 constexpr ostream &operator<<(ostream &os, const ModInt &p) noexcept {
return os << p.x;
}
friend constexpr istream &operator>>(istream &is, ModInt &a) noexcept {
int64_t t = 0;
is >> t;
a = ModInt<mod>(t);
return (is);
}
constexpr int get_mod() { return mod; }
};
using mint = ModInt<>;
int n;
vector<int> a;
vector<mint> cnt;
mint solve();
int main() {
cin >> n;
a.resize(n);
for (auto &p : a) cin >> p;
cout << solve() << endl;
return 0;
}
mint solve() {
if (n == 2) return 2 * (a[1] - a[0]);
mint res = 0;
cnt.assign(2501, 0);
a.push_back(a[n - 1]);
for (int x = 1; x <= 2500; ++x) {
vector<int> memo(n, 0);
for (int i = 0; i < n; ++i) {
int fi = i;
memo[i] = i;
while (i + 1 < n && a[i + 1] - a[i] <= x) memo[++i] = fi;
}
SegmentTree<mint> seg[2];
auto f = [](mint l, mint r) { return l + r; };
for (int i = 0; i < 2; ++i) seg[i] = SegmentTree<mint>(n + 1, f, 0);
seg[0].update(0, 1);
seg[1].update(0, 1);
for (int i = 0; i < n; ++i)
for (int j = 0; j < 2; ++j) {
int l = memo[i],
r = (int)(lower_bound(a.begin(), a.end(), a[i + 1] - x) -
a.begin()) +
1;
l = max(l, r);
mint now = memo[i] == 0;
if (l < i + 1) now += seg[1 ^ j].query(l, i + 1);
seg[j].update(i + 1, now);
}
cnt[x] = seg[0].query(n, n + 1) + seg[1].query(n, n + 1);
res += (cnt[x] - cnt[x - 1]) * x;
}
return res / 2;
}
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