結果

問題 No.1102 Remnants
ユーザー 👑 emthrmemthrm
提出日時 2020-07-03 21:51:38
言語 C++17
(gcc 13.2.0 + boost 1.83.0)
結果
AC  
実行時間 1,880 ms / 2,000 ms
コード長 4,542 bytes
コンパイル時間 2,381 ms
コンパイル使用メモリ 211,052 KB
実行使用メモリ 7,176 KB
最終ジャッジ日時 2023-10-17 01:19:14
合計ジャッジ時間 20,574 ms
ジャッジサーバーID
（参考情報） 		judge11 / judge14
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
4,348 KB
testcase_01 AC 2 ms
4,348 KB
testcase_02 AC 1,824 ms
4,348 KB
testcase_03 AC 1,762 ms
4,348 KB
testcase_04 AC 2 ms
4,348 KB
testcase_05 AC 39 ms
6,384 KB
testcase_06 AC 9 ms
4,348 KB
testcase_07 AC 1,880 ms
7,176 KB
testcase_08 AC 2 ms
4,348 KB
testcase_09 AC 4 ms
4,348 KB
testcase_10 AC 1,187 ms
4,348 KB
testcase_11 AC 504 ms
4,348 KB
testcase_12 AC 849 ms
4,348 KB
testcase_13 AC 4 ms
4,348 KB
testcase_14 AC 24 ms
5,064 KB
testcase_15 AC 19 ms
4,536 KB
testcase_16 AC 47 ms
6,912 KB
testcase_17 AC 45 ms
6,648 KB
testcase_18 AC 48 ms
6,648 KB
testcase_19 AC 18 ms
4,360 KB
testcase_20 AC 610 ms
4,348 KB
testcase_21 AC 1,503 ms
5,328 KB
testcase_22 AC 1,731 ms
6,120 KB
testcase_23 AC 1,415 ms
5,328 KB
testcase_24 AC 1,029 ms
4,800 KB
testcase_25 AC 823 ms
6,648 KB
testcase_26 AC 89 ms
4,348 KB
testcase_27 AC 1,351 ms
4,348 KB
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 # 

#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;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const 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() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int mod = MOD;
struct ModInt {
  unsigned val;
  ModInt(): val(0) {}
  ModInt(ll x) : val(x >= 0 ? x % mod : x % mod + mod) {}
  ModInt pow(ll exponent) const {
    ModInt tmp = *this, res = 1;
    while (exponent > 0) {
      if (exponent & 1) res *= tmp;
      tmp *= tmp;
      exponent >>= 1;
    }
    return res;
  }
  ModInt &operator+=(const ModInt &x) { if((val += x.val) >= mod) val -= mod; return *this; }
  ModInt &operator-=(const ModInt &x) { if((val += mod - x.val) >= mod) val -= mod; return *this; }
  ModInt &operator*=(const ModInt &x) { val = static_cast<unsigned long long>(val) * x.val % mod; return *this; }
  ModInt &operator/=(const ModInt &x) {
    // assert(__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;
      swap(a -= tmp * b, b);
      swap(u -= tmp * v, v);
    }
    return *this *= u;
  }
  bool operator==(const ModInt &x) const { return val == x.val; }
  bool operator!=(const ModInt &x) const { return val != x.val; }
  bool operator<(const ModInt &x) const { return val < x.val; }
  bool operator<=(const ModInt &x) const { return val <= x.val; }
  bool operator>(const ModInt &x) const { return val > x.val; }
  bool operator>=(const ModInt &x) const { return val >= x.val; }
  ModInt &operator++() { if (++val == mod) val = 0; return *this; }
  ModInt operator++(int) { ModInt res = *this; ++*this; return res; }
  ModInt &operator--() { val = (val == 0 ? mod : val) - 1; return *this; }
  ModInt operator--(int) { ModInt res = *this; --*this; return res; }
  ModInt operator+() const { return *this; }
  ModInt operator-() const { return ModInt(val ? mod - val : 0); }
  ModInt operator+(const ModInt &x) const { return ModInt(*this) += x; }
  ModInt operator-(const ModInt &x) const { return ModInt(*this) -= x; }
  ModInt operator*(const ModInt &x) const { return ModInt(*this) *= x; }
  ModInt operator/(const ModInt &x) const { return ModInt(*this) /= x; }
  friend ostream &operator<<(ostream &os, const ModInt &x) { return os << x.val; }
  friend istream &operator>>(istream &is, ModInt &x) { ll val; is >> val; x = ModInt(val); return is; }
};
ModInt abs(const ModInt &x) { return x; }
struct Combinatorics {
  int val; // "val!" and "mod" must be disjoint.
  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(i, 1, val + 1) 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(i, 1, val + 1) inv[i] = fact[i - 1] * fact_inv[i];
  }
  ModInt nCk(int n, int k) const {
    if (n < 0 || n < k || k < 0) return ModInt(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 ModInt(0);
    // assert(n <= val);
    return fact[n] * fact_inv[n - k];
  }
  ModInt nHk(int n, int k) const {
    if (n < 0 || k < 0) return ModInt(0);
    return (k == 0 ? ModInt(1) : nCk(n + k - 1, k));
  }
};

int main() {
  int n, k; cin >> n >> k;
  ModInt k_fact = 1;
  FOR(i, 1, k + 1) k_fact *= i;
  ModInt k_fact_inv = ModInt(1) / k_fact;
  vector ad(n + 1, k_fact);
  FOR(i, 1, n + 1) ad[i] = ad[i - 1] * (k + i);
  Combinatorics com(n);
  function<ModInt(int)> calc = [&](int m) {
    return ad[m] * com.fact_inv[m] * k_fact_inv;
  };
  vector<int> a(n); REP(i, n) cin >> a[i];
  ModInt ans = 0;
  REP(i, n) {
    // cout << calc(i) << ' ' << calc(n - 1 - i) << '\n';
    ans += calc(i) * calc(n - 1 - i) * a[i];
  }
  cout << ans << '\n';
  return 0;
}
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