Submission #1001152

---

Source Code Expand

#include <bits/stdc++.h>
using namespace std;

long long mod=1000000007ll;
long long v[10010],P[10010],rP[10010];

void pre(int N)
{
  v[1]=1;
  for(int i=2;i<N;i++){
    v[i]=(mod-mod/i)*v[mod%i]%mod;
  }
  P[0]=rP[0]=1ll;
  for(int i=1;i<N;i++){
    P[i]=P[i-1]*i%mod;
    rP[i]=rP[i-1]*v[i]%mod;
  }
}

long long C(int a,int b)
{
  return P[a]*rP[b]%mod*rP[a-b]%mod;
}

int main()
{
  pre(10010);
  int n,a,b,c;
  scanf("%d%d%d%d",&n,&a,&b,&c);
  if(b%2!=0){
    printf("0\n");
    return 0;
  }
  b/=2;
  long long ans=0ll;
  for(int x=0;x<=a;x++){
    for(int y=0;(a-x)+3*y<=c;y++){
      int m=a+y,r=c-(a-x)-3*y;
      long long P=C(m,a)%mod*C(a,x)%mod,Q;
      if(b==0){
	Q=(r==0?1:0);
      }
      else{
	Q=C(b+m,m)*C(r+b-1,b-1)%mod;
      }
      ans+=P*Q%mod;
      ans%=mod;
    }
  }
  printf("%lld\n",ans);
  return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:29:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d%d",&n,&a,&b,&c);
                                ^

Judge Result