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ID题目提交者结果用时内存语言文件大小提交时间测评时间
#93967#6137. Sub-cycle GraphksunhokimTL 12ms6808kbC++202.2kb2023-04-04 11:58:232023-04-04 11:58:26

Judging History

你现在查看的是最新测评结果

  • [2023-08-10 23:21:45]
  • System Update: QOJ starts to keep a history of the judgings of all the submissions.
  • [2023-04-04 11:58:26]
  • 评测
  • 测评结果:TL
  • 用时:12ms
  • 内存:6808kb
  • [2023-04-04 11:58:23]
  • 提交

answer

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

// Modular Integer
// does arithmetics (mod P) automatically
template<class T> T power(T a, ll b) { T res = 1; for (; b; b /= 2, a *= a) { if (b % 2) { res *= a; } } return res; }
int P = 1000000007; // 1000000007
struct zint {
  int x;
  // assumes -P <= x <= 2P
  int norm(int x) const { if (x < 0) { x += P; } if (x >= P) { x -= P; } return x; }
  zint(int x = 0) : x(norm(x)) {}
  zint(ll x) : x(norm((int)(x % P))) {}
  int val() const { return x; }
  zint operator-() const { return zint(norm(P - x)); }
  zint inv() const { assert(x != 0); return power(*this, P - 2); }
  zint& operator*=(const zint& rhs) { x = (int)(ll(x) * rhs.x % P); return *this; }
  zint& operator+=(const zint& rhs) { x = norm(x + rhs.x); return *this; }
  zint& operator-=(const zint& rhs) { x = norm(x - rhs.x); return *this; }
  zint& operator/=(const zint& rhs) { return *this *= rhs.inv();}
  friend zint operator*(const zint& lhs, const zint& rhs) { zint res = lhs; res *= rhs; return res; }
  friend zint operator+(const zint& lhs, const zint& rhs) { zint res = lhs; res += rhs; return res; }
  friend zint operator-(const zint& lhs, const zint& rhs) { zint res = lhs; res -= rhs; return res; }
  friend zint operator/(const zint& lhs, const zint& rhs) { zint res = lhs; res /= rhs; return res; }
  friend ostream& operator << (ostream& out, const zint& rhs) { out << rhs.val(); return out; }
  friend istream& operator >> (istream& in, zint& rhs) { ll x; in >> x; rhs = zint(x); return in; }
};

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);

  const int N = 1e6;
  vector<zint> facts(N+1);
  facts[0] = 1;
  for (int i=1;i<=N;i++){
    facts[i] = i*facts[i-1];
  }
  int t;
  cin >> t;
  while (t--) {
    ll n,m;
    cin >> n >> m;
    if (m > n) {
      cout << 0 << "\n";
      continue;
    }
    if (m == n) {
      cout << (facts[n-1]/2).val() << "\n";
      continue;
    }
    zint ans = 0;
    for (int i=1;i<=n-m;i++){
      if (m < i) break;
      //mint ncr = facts[m-1]/(facts[i-1]*facts[m-i]);
      ans += facts[m-1]*facts[n]/(max(n-m-i,1ll)*i*power(zint(2),i)*facts[i-1]*facts[m-i]);
    }
    cout << ans.val() << "\n";
  }

}

详细

Test #1:

score: 100
Accepted
time: 12ms
memory: 6808kb

input:

3
4 2
4 3
5 3

output:

15
12
90

result:

ok 3 number(s): "15 12 90"

Test #2:

score: -100
Time Limit Exceeded

input:

17446
3 0
3 1
3 2
3 3
4 0
4 1
4 2
4 3
4 4
5 0
5 1
5 2
5 3
5 4
5 5
6 0
6 1
6 2
6 3
6 4
6 5
6 6
7 0
7 1
7 2
7 3
7 4
7 5
7 6
7 7
8 0
8 1
8 2
8 3
8 4
8 5
8 6
8 7
8 8
9 0
9 1
9 2
9 3
9 4
9 5
9 6
9 7
9 8
9 9
10 0
10 1
10 2
10 3
10 4
10 5
10 6
10 7
10 8
10 9
10 10
11 0
11 1
11 2
11 3
11 4
11 5
11 6
11 7
11...

output:

0
3
3
1
0
6
15
12
3
0
20
45
90
60
12
0
90
165
390
630
360
60
0
504
840
1680
3780
5040
2520
360
0
3360
5292
9240
19950
40320
45360
20160
2520
0
25920
39312
64008
119070
264600
468720
453600
181440
20160
0
226800
334800
521640
882630
1761480
3817800
5896800
4989600
1814400
181440
0
2217600
3207600
484...

result: