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QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#778434 | #6137. Sub-cycle Graph | 999# | AC ✓ | 171ms | 6224kb | C++14 | 1020b | 2024-11-24 14:36:32 | 2024-11-24 14:36:32 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
#define M 200005
#define P 1000000007
#define ll long long
int a[M],fc[M],inv[M],pw[M];
int C(int n,int m){
return 1ll*fc[n]*inv[m]%P*inv[n-m]%P;
}
void solve(){
int n,m;
scanf("%d%d",&n,&m);
if(m>n)puts("0");
else{
int ans=0;
if(m==0)puts("1");
else if(m==n){
if(n<=2)puts("0");
printf("%d\n",1ll*fc[n-1]*pw[1]%P);
}
else{
for(int i=2;i<=2*m&&i<=n;i+=2){
int d2=(2*m-i)/2,d0=n-i-d2,tp=1;
if(d0>=0){
tp=1ll*tp*C(n,i)%P*C(n-i,d2)%P;
tp=1ll*tp*C(i,i/2)%P*fc[i/2]%P*pw[i/2]%P;
tp=1ll*tp*fc[d2]%P*C(d2+i/2-1,i/2-1)%P;
ans=(ans+tp)%P;
}
}
printf("%d\n",ans);
}
}
}
int main(){
fc[0]=fc[1]=inv[0]=inv[1]=1;
for(int i=2;i<M;++i)fc[i]=1ll*i*fc[i-1]%P;
for(int i=2;i<M;++i)inv[i]=(P-1ll*P/i)*inv[P%i]%P;
pw[0]=1;pw[1]=inv[2];
for(int i=2;i<M;++i)pw[i]=1ll*pw[1]*pw[i-1]%P;
for(int i=2;i<M;++i)inv[i]=1ll*inv[i-1]*inv[i]%P;
int t;
scanf("%d",&t);
while(t--)solve();
}
Details
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Test #1:
score: 100
Accepted
time: 5ms
memory: 6224kb
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: 171ms
memory: 6208kb
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