結果

問題 No.1081 和の和
ユーザー pyranine
提出日時 2020-12-21 19:12:02
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 2 ms / 2,000 ms
コード長 4,602 bytes
コンパイル時間 1,780 ms
コンパイル使用メモリ 174,412 KB
実行使用メモリ 5,376 KB
最終ジャッジ日時 2024-09-21 13:03:56
合計ジャッジ時間 2,363 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 * 8
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;
template <int mod>
struct ModInt {
  using lint = int64_t;
  static int get_mod() { return mod; }
  static int get_primitive_root() {
    static int primitive_root = 0;
    if (!primitive_root) {
      primitive_root = [&](){
        std::set<int> fac;
        int v = mod - 1;
        for (lint i = 2; i * i <= v; i++) while (v % i == 0) fac.insert(i), v /= i;
        if (v > 1) fac.insert(v);
        for (int g = 1; g < mod; g++) {
          bool ok = true;
          for (auto i : fac) if (ModInt(g).power((mod - 1) / i) == 1) { ok = false; break; }
          if (ok) return g;
        }
        return -1;
      }();
    }
    return primitive_root;
  }
  int val;
  constexpr ModInt() : val(0) {}
  constexpr ModInt &_setval(lint v) { val = (v >= mod ? v - mod : v); return *this; }
  constexpr ModInt(lint v) { _setval(v % mod + mod); }
  explicit operator bool() const { return val != 0; }
  constexpr ModInt operator+(const ModInt &x) const { return ModInt()._setval((lint)val + x.val); }
  constexpr ModInt operator-(const ModInt &x) const { return ModInt()._setval((lint)val - x.val + mod); }
  constexpr ModInt operator*(const ModInt &x) const { return ModInt()._setval((lint)val * x.val % mod); }
  constexpr ModInt operator/(const ModInt &x) const { return ModInt()._setval((lint)val * x.inv() % mod); }
  constexpr ModInt operator-() const { return ModInt()._setval(mod - val); }
  constexpr ModInt &operator+=(const ModInt &x) { return *this = *this + x; }
  constexpr ModInt &operator-=(const ModInt &x) { return *this = *this - x; }
  constexpr ModInt &operator*=(const ModInt &x) { return *this = *this * x; }
  constexpr ModInt &operator/=(const ModInt &x) { return *this = *this / x; }
  friend constexpr ModInt operator+(lint a, const ModInt &x) { return ModInt()._setval(a % mod + x.val); }
  friend constexpr ModInt operator-(lint a, const ModInt &x) { return ModInt()._setval(a % mod - x.val + mod); }
  friend constexpr ModInt operator*(lint a, const ModInt &x) { return ModInt()._setval(a % mod * x.val % mod); }
  friend constexpr ModInt operator/(lint a, const ModInt &x) { return ModInt()._setval(a % mod * x.inv() % mod); }
  constexpr bool operator==(const ModInt &x) const { return val == x.val; }
  constexpr bool operator!=(const ModInt &x) const { return val != x.val; }
  bool operator<(const ModInt &x) const { return val < x.val; }  // To use std::map<ModInt, T>
  friend std::istream &operator>>(std::istream &is, ModInt &x) { lint t; is >> t; x = ModInt(t); return is; }
  friend std::ostream &operator<<(std::ostream &os, const ModInt &x) { os << x.val;  return os; }
  constexpr lint power(lint n) const {
      lint ans = 1, tmp = this->val;
      while (n) {
          if (n & 1) ans = ans * tmp % mod;
          tmp = tmp * tmp % mod;
          n /= 2;
      }
      return ans;
  }
  constexpr lint inv() const { return this->power(mod - 2); }
  constexpr ModInt operator^(lint n) const { return ModInt(this->power(n)); }
  constexpr ModInt &operator^=(lint n) { return *this = *this ^ n; }
  inline ModInt fac() const {
    static std::vector<ModInt> facs;
    int l0 = facs.size();
    if (l0 > this->val) return facs[this->val];
    facs.resize(this->val + 1);
    for (int i = l0; i <= this->val; i++) facs[i] = (i == 0 ? ModInt(1) : facs[i - 1] * ModInt(i));
    return facs[this->val];
  }
  ModInt doublefac() const {
    lint k = (this->val + 1) / 2;
    if (this->val & 1) return ModInt(k * 2).fac() / ModInt(2).power(k) / ModInt(k).fac();
    else return ModInt(k).fac() * ModInt(2).power(k);
  }
  ModInt nCr(const ModInt &r) const {
    if (this->val < r.val) return ModInt(0);
    return this->fac() / ((*this - r).fac() * r.fac());
  }
  ModInt sqrt() const {
    if (val == 0) return 0;
    if (mod == 2) return val;
    if (power((mod - 1) / 2) != 1) return 0;
    ModInt b = 1;
    while (b.power((mod - 1) / 2) == 1) b += 1;
    int e = 0, m = mod - 1;
    while (m % 2 == 0) m >>= 1, e++;
    ModInt x = power((m - 1) / 2), y = (*this) * x * x;
    x *= (*this);
    ModInt z = b.power(m);
    while (y != 1) {
      int j = 0;
      ModInt t = y;
      while (t != 1) j++, t *= t;
      z = z.power(1LL << (e - j - 1));
      x *= z, z *= z, y *= z;
      e = j;
    }
    return ModInt(std::min(x.val, mod - x.val));
  }
};
using mint = ModInt<1000000007>;
int main() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++) cin >> a[i];
  mint ret = 0;
  for (int i = 0; i < n; i++) {
    ret += a[i] * mint(n - 1).nCr(i);
  }
  cout << ret << '\n';
  return 0;
}
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