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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 |
---|---|---|---|---|---|---|---|---|---|
#143924 | #6137. Sub-cycle Graph | PhantomThreshold# | WA | 181ms | 9460kb | C++20 | 1.3kb | 2023-08-21 15:03:15 | 2023-08-21 15:03:16 |
Judging History
answer
#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int maxn = 510000;
const int mod = 1e9+7;
const int inv2 = (mod+1)>>1;
int pw(int x,int k)
{
int re=1;
for(;k;k>>=1,x=(ll)x*x%mod) if(k&1)
re=(ll)re*x%mod;
return re;
}
int inv(int x){ return pw(x,mod-2); }
int fac[maxn],ifac[maxn],ipw2[maxn];
void pre()
{
fac[0]=1; for(int i=1;i<maxn;i++) fac[i]=(ll)fac[i-1]*i%mod;
ifac[maxn-1]=inv(fac[maxn-1]);
for(int i=maxn-2;i>=0;i--) ifac[i]=(ll)ifac[i+1]*(i+1)%mod;
ipw2[0]=1;
for(int i=1;i<maxn;i++) ipw2[i]=(ll)ipw2[i-1]*inv2%mod;
}
int C(int i,int j)
{
if(i<j || j<0 || i<0) return 0;
return (ll)fac[i]*ifac[j]%mod*ifac[i-j]%mod;
}
int solve(int n,int m)
{
if(m==0)
{
if(n==0) return 1;
else return 0;
}
return (ll)C(n-1-1-2*(m-1)+1+m-2,m-1)*fac[n]%mod*ifac[m]%mod*ipw2[m]%mod;
}
signed main()
{
ios_base::sync_with_stdio(false);
//freopen("tmp.in","r",stdin);
pre();
int Tcase; cin>>Tcase;
while(Tcase--)
{
int n,m; cin>>n>>m;
if(m>n-1)
{
cout<<0<<'\n';
continue;
}
int k= n-m;
ll ans=0;
for(int p=0;p<=k;p++)
{
// ll tans=ans;
ans+=(ll)C(n,p)*solve( n-p,k-p )%mod;
// cerr<<p<<" : "<<ans-tans<<endl;
}
cout<<ans%mod<<'\n';
}
return 0;
}
詳細信息
Test #1:
score: 100
Accepted
time: 9ms
memory: 9392kb
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: 181ms
memory: 9460kb
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 0 1 6 15 12 0 1 10 45 90 60 0 1 15 105 375 630 360 0 1 21 210 1155 3465 5040 2520 0 1 28 378 2940 13545 35280 45360 20160 0 1 36 630 6552 42525 170100 393120 453600 181440 0 1 45 990 13230 114345 643545 2286900 4762800 4989600 1814400 0 1 55 1485 24750 273735 2047815 10239075 32848200 62370000...
result:
wrong answer 4th numbers differ - expected: '1', found: '0'