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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 |
---|---|---|---|---|---|---|---|---|---|
#94946 | #6137. Sub-cycle Graph | George_Plover# | WA | 74ms | 4932kb | C++23 | 1.3kb | 2023-04-08 14:07:31 | 2023-04-08 14:07:34 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
#define For(i,a,b) for(int i=(a);i<=(b);i++)
#define Rof(i,a,b) for(int i=(a);i>=(b);i--)
template<class T> void chkmin(T &x,T y){if(y<x)x=y;}
typedef long long ll;
const int N=100005,MOD=1000000007;
int mo(int x){return x>=MOD?x-MOD:x;}
void moplus(int &x,int y){x=mo(x+y);}
int ksm(int a,int b)
{
int res=1;
while(b)
{
if(b&1)res=1ll*res*a%MOD;
b>>=1;
a=1ll*a*a%MOD;
}
return res;
}
int fac[N],ifac[N],pow2[N];
void math_init(int n)
{
fac[0]=1;
For(i,1,n)fac[i]=1ll*fac[i-1]*i%MOD;
ifac[n]=ksm(fac[n],MOD-2);
Rof(i,n,1)ifac[i-1]=1ll*ifac[i]*i%MOD;
pow2[0]=1;
For(i,1,n)pow2[i]=mo(pow2[i-1]<<1);
}
int getC(int a,int b){return 1ll*fac[a]*ifac[b]%MOD*ifac[a-b]%MOD;}
void Main()
{
int n; ll m;
scanf("%d%lld",&n,&m);
if(m>n){printf("0\n"); return;}
if(m==n){printf("%d\n",fac[n-1]); return;}
int ans=0,f=1;
m=n-m;
For(i,0,min(m,n-m))
{
ans=(ans+1ll*f*pow2[m-i]%MOD*getC(m,i)%MOD*getC(n-i-1,n-m-i))%MOD;
f=MOD-f;
}
ans=1ll*ans*fac[n]%MOD*ifac[m]%MOD*ksm(pow2[m],MOD-2)%MOD;
printf("%d\n",ans);
}
int main()
{
math_init(100000);
int t;
scanf("%d",&t);
while(t--)Main();
}
詳細信息
Test #1:
score: 100
Accepted
time: 1ms
memory: 4932kb
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: 74ms
memory: 4928kb
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 2 1 6 15 12 6 1 10 45 90 60 24 1 15 105 375 630 360 120 1 21 210 1155 3465 5040 2520 720 1 28 378 2940 13545 35280 45360 20160 5040 1 36 630 6552 42525 170100 393120 453600 181440 40320 1 45 990 13230 114345 643545 2286900 4762800 4989600 1814400 362880 1 55 1485 24750 273735 2047815 10239075 ...
result:
wrong answer 4th numbers differ - expected: '1', found: '2'