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IDProblemSubmitterResultTimeMemoryLanguageFile sizeSubmit timeJudge time
#810930#6137. Sub-cycle GraphJerrywangAC ✓286ms8268kbC++141.6kb2024-12-12 13:33:582024-12-12 13:34:00

Judging History

你现在查看的是最新测评结果

  • [2024-12-12 13:34:00]
  • 评测
  • 测评结果:AC
  • 用时:286ms
  • 内存:8268kb
  • [2024-12-12 13:33:58]
  • 提交

answer

// P9896 [ICPC2018 Qingdao R] Sub-cycle Graph 
#include <cstdio>
#include <iostream>
#define ll long long
#define rep(i, s, t) for(int i=s; i<=t; ++i)
#define debug(x) cerr<<#x<<":"<<x<<endl;
const int N=100010, mod=1e9+7;
using namespace std;
char buf[1<<23], *p1=buf, *p2=buf;
#define gc() (p1==p2 && (p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
inline int read()
{
    int x=0, f=1; char c=gc();
    while(c<'0' || c>'9') c=='-' && (f=-1), c=gc();
    while('0'<=c && c<='9') x=(x<<3)+(x<<1)+c-'0', c=gc();
    return x*f;
}

int T, n, m; ll res, tmp;
ll fac[N], inv[N], inv2[N], Inv2;
ll qp(ll x, ll y=mod-2)
{
    ll res=1;
    for(; y; y>>=1, x=x*x%mod) if(y&1) res=res*x%mod;
    return res;
}
ll C(int n, int m)
{
    if(n<m) return 0;
    return fac[n]*inv[n-m]%mod*inv[m]%mod;
}
void solve()
{
    n=read(), m=read(); res=-1;
    if(!m) res=1;
    if(m>n) res=0;
    if(m==n) res=fac[n-1]*Inv2%mod;
    if(~res) {printf("%lld\n", res); return;}
    res=0;
    rep(x, 1, n/2)
    {
        int d1=x+x, d2=(m+m-d1)>>1, d3=n-d1-d2;
        tmp=C(n, d1)*C(n-d1, d2)%mod;
        tmp=tmp*C(d1, x)%mod*fac[x]%mod*inv2[x]%mod;
        tmp=tmp*fac[d2]%mod*C(d2+x-1, x-1)%mod;
        res=(res+tmp)%mod;
    }
    printf("%lld\n", res);
}

int main()
{
#ifdef Jerrywang
    freopen("../in.txt", "r", stdin);
#endif
    fac[0]=1; rep(i, 1, N-1) fac[i]=fac[i-1]*i%mod;
    inv[N-1]=qp(fac[N-1]), Inv2=qp(2);
    for(int i=N-1; i; i--) inv[i-1]=inv[i]*i%mod;
    inv2[0]=1; rep(i, 1, N-1) inv2[i]=inv2[i-1]*Inv2%mod;
    T=read(); while(T--) solve();
    return 0;
}

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100
Accepted
time: 0ms
memory: 7416kb

input:

3
4 2
4 3
5 3

output:

15
12
90

result:

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

Test #2:

score: 0
Accepted
time: 286ms
memory: 8268kb

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:

ok 17446 numbers