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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#190458#6137. Sub-cycle GraphZhou_JKWA 167ms5200kbC++231.4kb2023-09-28 21:57:132023-09-28 21:57:14

Judging History

你现在查看的是最新测评结果

  • [2023-09-28 21:57:14]
  • 评测
  • 测评结果:WA
  • 用时:167ms
  • 内存:5200kb
  • [2023-09-28 21:57:13]
  • 提交

answer

#include<iostream>
#include<cstdio>
using namespace std;
const int N=100005;
const int MOD=1000000007;
const int INV2=500000004;
int qpow(int a,int b)
{
    int res=1;
    while(b)
    {
        if(b&1) res=(long long)res*a%MOD;
        a=(long long)a*a%MOD,b>>=1;
    }
    return res;
}
int getinv(int a)
{
    return qpow(a,MOD-2);
}
int fac[N+N],ifac[N+N];
void init(int n=200000)
{
    fac[0]=1;
    for(int i=1;i<=n;i++)
        fac[i]=(long long)fac[i-1]*i%MOD;
    ifac[n]=qpow(fac[n],MOD-2);
    for(int i=n;i>=1;i--)
        ifac[i-1]=(long long)ifac[i]*i%MOD;
    return;
}
int C(int n,int m)
{
    if(m>n) return 0;
    if(m==0||m==n) return 1;
    return (long long)fac[n]*ifac[m]%MOD*ifac[n-m]%MOD;
}
int n;
long long m;
void solve()
{
    cin>>n>>m;
    if(m>n) cout<<0<<"\n";
    else if(m==n)
    {
        int ans=(long long)fac[n-1]*INV2%MOD;
        cout<<ans<<"\n";
    }
    else
    {
        int ans=0;
        int pre=1;
        for(int i=1;i<=n-m;i++)
        {
            pre=(long long)pre*(2*i-1)%MOD;
            ans=(ans+(long long)C(n,n-m-i)*fac[m-i]%MOD*C(m-1,i-1)%MOD*C(m+i,2*i)%MOD*pre)%MOD;
        }
        cout<<ans<<"\n";
    }
    return;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr),cout.tie(nullptr);
    init();
    int T;
    cin>>T;
    while(T--)
        solve();
    return 0;
}

Details

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Test #1:

score: 100
Accepted
time: 3ms
memory: 5180kb

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: 167ms
memory: 5200kb

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
10
45
90
60
12
0
15
105
375
630
360
60
0
21
210
1155
3465
5040
2520
360
0
28
378
2940
13545
35280
45360
20160
2520
0
36
630
6552
42525
170100
393120
453600
181440
20160
0
45
990
13230
114345
643545
2286900
4762800
4989600
1814400
181440
0
55
1485
24750
273735
2047815
10239075
3...

result:

wrong answer 1st numbers differ - expected: '1', found: '0'