Submission #1014498

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Source Code Expand

#include <cstdio>
#include <cstring>
#include <vector>
#include<queue>
#include <algorithm>
#define pb push_back
using namespace std;
const int P = 1000000007;
const int N = 101010;
int n,a,b,c,i;
long long jc[N],ans;
long long ksm(long long a,long long b){
	if (b==0){
		return 1;
	}
	long long ans=ksm(a,b/2);
	ans=ans*ans%P;
	if (b%2==1) ans=ans*a%P;
	return ans;
}
long long cc(int a,int b){
	return jc[b]*ksm(jc[a]*jc[b-a]%P,P-2)%P;
}
int main(){
	jc[0]=1;
	for (i=1;i<=20000;i++)
		jc[i]=(jc[i-1]*i)%P;
	scanf("%d%d%d%d",&n,&a,&b,&c);
	if (b%2==1){
		printf("0\n");
		return 0;
	}
	//printf("%lld\n",cc(2,5));
	int ds=a+b/2;
	for (i=0;i<=a;i++){
		int t=a-i;
		if (t>c) continue;
		int tt=c-t;
		for (int j=0;j*3<=tt;j++){
			long long tmp=cc(j,ds+j)*cc(i,ds)%P*cc(a-i,ds-i)%P;
			int ttt=tt-3*j;
			if ((b==0)&&(ttt)) continue;
			if (b/2-1>=0) tmp=tmp*cc(b/2-1,b/2+ttt-1)%P;
			ans=(ans+tmp)%P;
		}
	}
	printf("%lld\n",ans);
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:28:31: 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