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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
#559096#6137. Sub-cycle GraphpigstdWA 125ms5996kbC++201.6kb2024-09-11 20:11:512024-09-11 20:11:51

Judging History

你现在查看的是最新测评结果

  • [2024-09-11 20:11:51]
  • 评测
  • 测评结果:WA
  • 用时:125ms
  • 内存:5996kb
  • [2024-09-11 20:11:51]
  • 提交

answer

#include<bits/stdc++.h>
#define int long long
#define ull unsigned long long
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define x first
#define y second
#define vi vector<int>
#define vpi vector<pii>
#define all(x) (x).begin(),(x).end()
using namespace std;

inline int read()
{
    char c=getchar();int x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}

const int Mod=1e9+7;
const int M=1e5+10;
const int inv2=(Mod+1)/2;
int n,T,fac[M],ifac[M],pwiv2[M];

int poww(int a,int b=Mod-2)
{
    int res=1;
    while(b)
    {
        if (b&1)res=res*a%Mod;
        a=a*a%Mod,b>>=1;
    }
    return res;
}

void init(int n)
{
    fac[0]=pwiv2[0]=1;
    for (int i=1;i<=n;i++)fac[i]=fac[i-1]*i%Mod,pwiv2[i]=pwiv2[i-1]*inv2%Mod;
    ifac[n]=poww(fac[n]);
    for (int i=n;i>=1;i--)ifac[i-1]=ifac[i]*i%Mod;
}

int C(int m,int n)
{
    if (n<0||m<n)return 0;
    return fac[m]*ifac[n]%Mod*ifac[m-n]%Mod;
}

int calc(int m,int n)
{
    if (m<2*n)return 0;
    if (n==0)return m==0;
    return C(m-n-1,n-1);
}

signed main()
{
    init(1e5);
    int T=read();
    while(T--)
    {
        int n=read(),m=read();
        if (m>n)
        {
            puts("0");
            continue;
        }
        if (m==n)
        {
            cout<<fac[n-1]/2<<'\n';
            continue;
        }
        int ans=0;
        int k=n-m;
        for (int i=0;i<=k;i++)
            ans=(ans+pwiv2[k-i]*fac[n-i]%Mod*C(n,i)%Mod*ifac[k-i]%Mod*calc(n-i,k-i))%Mod;
        cout<<ans<<'\n';
    }
    return 0;
}

详细

Test #1:

score: 100
Accepted
time: 2ms
memory: 5996kb

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: 125ms
memory: 5928kb

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 130th numbers differ - expected: '589145299', found: '89145295'