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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 |
---|---|---|---|---|---|---|---|---|---|
#93490 | #6137. Sub-cycle Graph | lam | WA | 139ms | 6504kb | C++14 | 1.4kb | 2023-03-31 22:32:41 | 2023-03-31 22:32:42 |
Judging History
answer
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int maxn = 2e5 + 10;
const int mod = 1e9 + 7;
int p[maxn],inv[maxn];
int n,m;
int ppow(int x, int y)
{
int temp=1LL;
while (y)
{
if (y&1) temp=temp*x%mod;
x=x*x%mod;
y/=2;
}
return temp;
}
void precalc()
{
int lim = 2e5;
p[0]=1LL;
for (int i=1; i<=lim; i++) p[i]=p[i-1]*i%mod;
inv[lim] = ppow(p[lim],mod-2);
for (int i=lim-1; i>=0; i--) inv[i]=inv[i+1]*(i+1)%mod;
}
int C(int x, int y)
{
if (x>y) return 0;
return p[y]*inv[x]%mod*inv[y-x]%mod;
}
void xuly()
{
cin>>n>>m;
if (m>n)
{
cout<<"0\n";
return;
}
if (m==0)
{
cout<<1<<'\n';
return;
}
if (m==n)
{
int ans = p[n-1]*ppow(2,mod-2)%mod;
cout<<ans<<'\n';
return;
}
int ans = 0;
int pre = 1LL;
for (int i=1; i<=n-m; i++)
{
if (m+i<2*i) continue;
int val = C(n-m-i,n)*pre%mod * C(2*i,m+i)%mod;
pre = pre*(2*i+1);
val = val*p[m-i]%mod*C(i-1,m-1)%mod;
// cout<<i<<" = "<<val<<'\n';
ans=(ans+val)%mod;
}
cout<<ans<<'\n';
}
/**
n-2*i cho
**/
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
precalc();
int tt; cin>>tt;
while (tt--) xuly();
}
详细
Test #1:
score: 100
Accepted
time: 2ms
memory: 6504kb
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: 139ms
memory: 6496kb
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 568th numbers differ - expected: '162808277', found: '-419535731'