Submission #3357436

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Source Code Expand

#include<cstdio>

const int P=1000000007;
int n,d[305],fac[305],inv[305],f[305][305][2],ans;

int power(int a,int x){
	int ans=1;
	for(;x;x>>=1,a=1ll*a*a%P)if(x&1)ans=1ll*ans*a%P;
	return ans;
}
void upd(int &x,int y){x=x+y>=P?x+y-P:x+y;}

int main(){
	scanf("%d",&n);
	bool cir=true;
	for(int i=1;i<=n;i++)scanf("%d",d+i),cir&=d[i]==2;
	for(int i=fac[0]=1;i<=n;i++)fac[i]=1ll*fac[i-1]*i%P;
	inv[n]=power(fac[n],P-2);
	for(int i=n;i;i--)inv[i-1]=1ll*inv[i]*i%P;
	if(cir&&n>=3)ans=1ll*fac[n-1]*inv[2]%P;
	f[0][0][0]=1;
	for(int i=0;i<n;i++)
		for(int j=0;j<=n;j++)
			for(int k=0;k<2;k++){
				if(!f[i][j][k])continue;
				upd(f[i+1][j][k],f[i][j][k]);
				if(d[i+1]>=2)
					upd(f[i+1][j+1][k],1ll*f[i][j][k]*(d[i+1]-1)%P);
				if(!k&&d[i+1]>=3)
					upd(f[i+1][j+1][1],1ll*f[i][j][k]*(d[i+1]-1)%P*(d[i+1]-2)%P);
			}
	for(int i=3;i<n;i++)
		upd(ans,1ll*fac[i-1]*inv[2]%P*f[n][i][1]%P*fac[n-i-1]%P);
	for(int i=1;i<=n;i++)ans=1ll*ans*inv[d[i]-1]%P;
	printf("%d\n",ans);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:14:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
./Main.cpp:16:51: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<=n;i++)scanf("%d",d+i),cir&=d[i]==2;
                                                   ^

Judge Result