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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 |
---|---|---|---|---|---|---|---|---|---|
#646051 | #6137. Sub-cycle Graph | qinglu09 | WA | 101ms | 6764kb | C++14 | 1.4kb | 2024-10-16 21:04:50 | 2024-10-16 21:04:51 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
#define debug(x) cout<<#x<<": "<<x<<endl
const ll mod=1e9+7;
const ll N=1e5+10;
ll qpow(ll a,ll b)
{
ll ans=1;
a%=mod;
while(b)
{
if(b&1) ans=ans*a%mod;
a=a*a%mod;
b>>=1;
}
return ans;
}
ll f[N],g[N],inv[N];
ll t[N];
void init_inverse1()//求1开始的连续逆元
{
inv[1]=1;
for(int i=2;i<N;i++)
inv[i]=(ll)(mod-mod/i)*inv[mod%i]%mod;
}
void init_combinatorial()
{
init_inverse1();//用init_inverse2()会稍微快一点
f[0]=g[0]=1;
for(int i=1;i<N;i++)
f[i]=(ll)f[i-1]*i%mod;
for(int i=1;i<N;i++)
g[i]=(ll)g[i-1]*inv[i]%mod;
}
ll getC(int n,int m)//n大m小
{
if(n<m) return 0;
return ((ll)f[n]*g[m]%mod)*g[n-m]%mod;
}
void solve()
{
ll n,m;
cin>>n>>m;
if(m>n)
{
cout<<0<<endl;
return;
}
else if(n==m)
{
cout<<f[n-1]*qpow(2,mod-2)%mod<<endl;
return;
}
ll k=n-m;
ll ans=qpow(qpow(2,mod-2),k);
ll now=0;
for(int i=0;i<=n-k;i++)
{
now+=(t[k-i]*getC(k,i)%mod)*(getC(n-i-1,n-k-i)%mod)*qpow(-1,i%2);
now%=mod;
}
ans=ans*now%mod;
ans=ans*f[n]%mod;
ans=ans*g[k]%mod;
cout<<ans<<endl;
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0),cout.tie(0);
int T=1;
cin>>T;
init_combinatorial();
t[0]=1;
for(int i=1;i<N;i++) t[i]=t[i-1]*2%mod;
while(T--)
{
solve();
}
return 0;
}
详细
Test #1:
score: 100
Accepted
time: 3ms
memory: 6764kb
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: 101ms
memory: 6724kb
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 275th numbers differ - expected: '157982055', found: '-842017952'