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 |
---|---|---|---|---|---|---|---|---|---|
#810930 | #6137. Sub-cycle Graph | Jerrywang | AC ✓ | 286ms | 8268kb | C++14 | 1.6kb | 2024-12-12 13:33:58 | 2024-12-12 13:34:00 |
Judging History
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;
}
详细
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