結果

問題 No.1102 Remnants
ユーザー fine
提出日時 2020-07-03 21:35:24
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 54 ms / 2,000 ms
コード長 3,399 bytes
コンパイル時間 1,946 ms
コンパイル使用メモリ 168,332 KB
実行使用メモリ 5,376 KB
最終ジャッジ日時 2024-09-16 23:09:10
合計ジャッジ時間 3,574 ms
ジャッジサーバーID
(参考情報)
judge1 / 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 * 25
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;
using ll = long long;
constexpr char newl = '\n';
// https://noshi91.hatenablog.com/entry/2019/03/31/174006
template <std::uint_fast64_t Modulus>
struct ModInt {
using u64 = std::uint_fast64_t;
static constexpr u64 MOD = Modulus;
u64 val;
constexpr ModInt(const u64 x = 0) noexcept : val(x % MOD) {}
constexpr ModInt operator+() const noexcept { return ModInt(*this); }
constexpr ModInt operator-() const noexcept {
ModInt res(*this);
if (res.val != 0) res.val = MOD - res.val;
return res;
}
constexpr bool operator==(const ModInt& rhs) const noexcept { return val == rhs.val; }
constexpr bool operator!=(const ModInt& rhs) const noexcept { return val != rhs.val; }
// prefix increment/decrement
constexpr ModInt& operator++() noexcept { return *this += ModInt(1); }
constexpr ModInt& operator--() noexcept { return *this -= ModInt(1); }
// postfix increment/decrement
constexpr ModInt operator++(int) noexcept {
ModInt tmp(*this);
++*this;
return tmp;
}
constexpr ModInt operator--(int) noexcept {
ModInt tmp(*this);
--*this;
return tmp;
}
constexpr ModInt operator+(const ModInt& rhs) const noexcept {
return ModInt(*this) += rhs;
}
constexpr ModInt operator-(const ModInt& rhs) const noexcept {
return ModInt(*this) -= rhs;
}
constexpr ModInt operator*(const ModInt& rhs) const noexcept {
return ModInt(*this) *= rhs;
}
constexpr ModInt operator/(const ModInt& rhs) const noexcept {
return ModInt(*this) /= rhs;
}
constexpr ModInt& operator+=(const ModInt& rhs) noexcept {
val += rhs.val;
if (val >= MOD) val -= MOD;
return *this;
}
constexpr ModInt& operator-=(const ModInt& rhs) noexcept {
if (val < rhs.val) val += MOD;
val -= rhs.val;
return *this;
}
constexpr ModInt& operator*=(const ModInt& rhs) noexcept {
val = val * rhs.val % MOD;
return *this;
}
// prime Modulus only
constexpr ModInt& operator/=(const ModInt& rhs) noexcept {
return *this *= rhs.inv();
}
// prime Modulus only
constexpr ModInt inv() const noexcept {
return pow(*this, MOD - 2);
}
};
template<std::uint_fast64_t Modulus>
constexpr ModInt<Modulus> pow(ModInt<Modulus> x, std::uint_fast64_t n) {
ModInt<Modulus> res(1);
while (n) {
if (n & 1) res *= x;
x *= x;
n >>= 1;
}
return res;
}
template<std::uint_fast64_t Modulus>
istream& operator>>(istream& is, ModInt<Modulus>& x) {
std::uint_fast64_t val;
is >> val;
x = ModInt<Modulus>(val);
return is;
}
template<std::uint_fast64_t Modulus>
ostream& operator<<(ostream& os, const ModInt<Modulus>& x) {
return os << x.val;
}
using mint = ModInt<1000000007>;
int main() {
cin.tie(nullptr);
ios::sync_with_stdio(false);
int n, K;
cin >> n >> K;
vector<mint> dp(n + 1, 1);
mint foo = 1, bar = 1;
for (int i = 1; i <= n; i++) {
dp[i] = foo / bar;
foo *= mint(K + i);
bar *= mint(i);
}
mint ans = 0;
for (int i = 0; i < n; i++) {
mint a;
cin >> a;
ans += a * dp[i + 1] * dp[n - i];
}
cout << ans << newl;
return 0;
}
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