QOJ.ac

QOJ

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
#93490#6137. Sub-cycle GraphlamWA 139ms6504kbC++141.4kb2023-03-31 22:32:412023-03-31 22:32:42

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.
  • [2023-03-31 22:32:42]
  • 评测
  • 测评结果:WA
  • 用时:139ms
  • 内存:6504kb
  • [2023-03-31 22:32:41]
  • 提交

answer

#include <bits/stdc++.h>
#define int long long
using namespace std;
const int maxn = 2e5 + 10;
const int mod = 1e9 + 7;
int p[maxn],inv[maxn];
int n,m;
int ppow(int x, int y)
{
    int temp=1LL;
    while (y)
    {
        if (y&1) temp=temp*x%mod;
        x=x*x%mod;
        y/=2;
    }
    return temp;
}
void precalc()
{
    int lim = 2e5;
    p[0]=1LL;
    for (int i=1; i<=lim; i++) p[i]=p[i-1]*i%mod;
    inv[lim] = ppow(p[lim],mod-2);
    for (int i=lim-1; i>=0; i--) inv[i]=inv[i+1]*(i+1)%mod;
}
int C(int x, int y)
{
    if (x>y) return 0;
    return p[y]*inv[x]%mod*inv[y-x]%mod;
}

void xuly()
{
    cin>>n>>m;
    if (m>n)
    {
        cout<<"0\n";
        return;
    }
    if (m==0)
    {
        cout<<1<<'\n';
        return;
    }
    if (m==n)
    {
        int ans = p[n-1]*ppow(2,mod-2)%mod;
        cout<<ans<<'\n';
        return;
    }
    int ans = 0;
    int pre = 1LL;
    for (int i=1; i<=n-m; i++)
    {
        if (m+i<2*i) continue;
        int val = C(n-m-i,n)*pre%mod * C(2*i,m+i)%mod;
        pre = pre*(2*i+1);
        val = val*p[m-i]%mod*C(i-1,m-1)%mod;
//        cout<<i<<" = "<<val<<'\n';
       ans=(ans+val)%mod;
    }
    cout<<ans<<'\n';
}
/**
n-2*i cho
**/

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr); cout.tie(nullptr);
    precalc();
    int tt; cin>>tt;
    while (tt--) xuly();
}

詳細信息

Test #1:

score: 100
Accepted
time: 2ms
memory: 6504kb

input:

3
4 2
4 3
5 3

output:

15
12
90

result:

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

Test #2:

score: -100
Wrong Answer
time: 139ms
memory: 6496kb

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:

1
3
3
1
1
6
15
12
3
1
10
45
90
60
12
1
15
105
375
630
360
60
1
21
210
1155
3465
5040
2520
360
1
28
378
2940
13545
35280
45360
20160
2520
1
36
630
6552
42525
170100
393120
453600
181440
20160
1
45
990
13230
114345
643545
2286900
4762800
4989600
1814400
181440
1
55
1485
24750
273735
2047815
10239075
3...

result:

wrong answer 568th numbers differ - expected: '162808277', found: '-419535731'