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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
#94946#6137. Sub-cycle GraphGeorge_Plover#WA 74ms4932kbC++231.3kb2023-04-08 14:07:312023-04-08 14:07:34

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.
  • [2023-04-08 14:07:34]
  • 评测
  • 测评结果:WA
  • 用时:74ms
  • 内存:4932kb
  • [2023-04-08 14:07:31]
  • 提交

answer

#include<bits/stdc++.h>
using namespace std;
#define For(i,a,b) for(int i=(a);i<=(b);i++)
#define Rof(i,a,b) for(int i=(a);i>=(b);i--)
template<class T> void chkmin(T &x,T y){if(y<x)x=y;}
typedef long long ll;
const int N=100005,MOD=1000000007;
int mo(int x){return x>=MOD?x-MOD:x;}
void moplus(int &x,int y){x=mo(x+y);}
int ksm(int a,int b)
{
    int res=1;
    while(b)
    {
        if(b&1)res=1ll*res*a%MOD;
        b>>=1;
        a=1ll*a*a%MOD;
    }
    return res;
}
int fac[N],ifac[N],pow2[N];
void math_init(int n)
{
    fac[0]=1;
    For(i,1,n)fac[i]=1ll*fac[i-1]*i%MOD;
    ifac[n]=ksm(fac[n],MOD-2);
    Rof(i,n,1)ifac[i-1]=1ll*ifac[i]*i%MOD;
    pow2[0]=1;
    For(i,1,n)pow2[i]=mo(pow2[i-1]<<1);
}
int getC(int a,int b){return 1ll*fac[a]*ifac[b]%MOD*ifac[a-b]%MOD;}
void Main()
{
    int n; ll m;
    scanf("%d%lld",&n,&m);
    if(m>n){printf("0\n"); return;}
    if(m==n){printf("%d\n",fac[n-1]); return;}
    int ans=0,f=1;
    m=n-m;
    For(i,0,min(m,n-m))
    {
        ans=(ans+1ll*f*pow2[m-i]%MOD*getC(m,i)%MOD*getC(n-i-1,n-m-i))%MOD;
        f=MOD-f;
    }
    ans=1ll*ans*fac[n]%MOD*ifac[m]%MOD*ksm(pow2[m],MOD-2)%MOD;
    printf("%d\n",ans);
}
int main()
{
    math_init(100000);
    int t;
    scanf("%d",&t);
    while(t--)Main();
}

详细

Test #1:

score: 100
Accepted
time: 1ms
memory: 4932kb

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: 74ms
memory: 4928kb

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
2
1
6
15
12
6
1
10
45
90
60
24
1
15
105
375
630
360
120
1
21
210
1155
3465
5040
2520
720
1
28
378
2940
13545
35280
45360
20160
5040
1
36
630
6552
42525
170100
393120
453600
181440
40320
1
45
990
13230
114345
643545
2286900
4762800
4989600
1814400
362880
1
55
1485
24750
273735
2047815
10239075
...

result:

wrong answer 4th numbers differ - expected: '1', found: '2'