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// Hacker Cup 2017
// Round 1
// Beach Umbrellas
// Jacob Plachta
#include <algorithm>
#include <functional>
#include <numeric>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <complex>
#include <cstdlib>
#include <ctime>
#include <cstring>
#include <cassert>
#include <string>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <sstream>
using namespace std;
#define LL long long
#define LD long double
#define PR pair<int,int>
#define Fox(i,n) for (i=0; i<n; i++)
#define Fox1(i,n) for (i=1; i<=n; i++)
#define FoxI(i,a,b) for (i=a; i<=b; i++)
#define FoxR(i,n) for (i=(n)-1; i>=0; i--)
#define FoxR1(i,n) for (i=n; i>0; i--)
#define FoxRI(i,a,b) for (i=b; i>=a; i--)
#define Foxen(i,s) for (i=s.begin(); i!=s.end(); i++)
#define Min(a,b) a=min(a,b)
#define Max(a,b) a=max(a,b)
#define Sz(s) int((s).size())
#define All(s) (s).begin(),(s).end()
#define Fill(s,v) memset(s,v,sizeof(s))
#define pb push_back
#define mp make_pair
#define x first
#define y second
template<typename T> T Abs(T x) { return(x<0 ? -x : x); }
template<typename T> T Sqr(T x) { return(x*x); }
const int INF = (int)1e9;
const LD EPS = 1e-12;
const LD PI = acos(-1.0);
bool Read(int &x)
{
char c,r=0,n=0;
x=0;
for(;;)
{
c=getchar();
if ((c<0) && (!r))
return(0);
if ((c=='-') && (!r))
n=1;
else
if ((c>='0') && (c<='9'))
x=x*10+c-'0',r=1;
else
if (r)
break;
}
if (n)
x=-x;
return(1);
}
#define MOD 1000000007
int fact[2005],ifact[2005];
PR GCD(int a,int b)
{
if (!b)
return(mp(1,0));
PR p=GCD(b,a%b);
return(mp(p.y,p.x-p.y*(a/b)));
}
int Add(int a,int b)
{
a+=b;
if (a>=MOD)
a-=MOD;
return(a);
}
int Mult(int a,int b)
{
return((LL)a*b%MOD);
}
int Div(int a,int b)
{
b=GCD(b,MOD).x;
if (b<0)
b+=MOD;
return(Mult(a,b));
}
int Ch(int n,int k)
{
if ((k<0) || (k>n))
return(0);
Min(k,n-k);
int i,v=1;
Fox(i,k)
v=Mult(v,n-i);
return(Mult(v,ifact[k]));
}
int main()
{
int T,t;
int N,M;
int i,j,s;
int ans;
int R[2000],cnt[4001];
Fox(i,2005)
{
fact[i]=i ? Mult(fact[i-1],i) : 1;
ifact[i]=Div(1,fact[i]);
}
Read(T);
Fox1(t,T)
{
s=ans=0;
Read(N),Read(M);
Fox(i,N)
Read(R[i]),s+=R[i]*2;
if (N==1)
{
ans=M;
goto Done;
}
Fill(cnt,0);
Fox(i,N)
Fox(j,N)
if (i!=j)
cnt[R[i]+R[j]]++;
Fox1(i,4000)
if (cnt[i])
ans=Add(ans,Mult(cnt[i],Mult(fact[N-2],Ch(M+i-s+N-1,N))));
Done:;
printf("Case #%d: %d\n",t,ans);
}
return(0);
} |