Submission #2232944

---

Source Code Expand

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;

const int N=20;
const int S=1<<N;
const int mod=1000000007;

int n,sz,x,y,m,ans;
int dp[S],g[N],cnt[S],bin[S];

void init(){
	int i,j;
	for (i=0;i<=sz;i++)
		for (j=0;j<n;j++) if ((i>>j)&1) cnt[i]++;
}

int main(){
	int i,s,ss,u,w;
	bin[0]=1; for (i=1;i<S;i++) bin[i]=2ll*bin[i-1]%mod;
	scanf("%d%d",&n,&m); sz=(1<<n)-1;
	for (i=1;i<=m;i++){
		scanf("%d%d",&x,&y); x--; y--;
		g[x]|=1<<y;
	}
	init();
	dp[0]=1;
	for (s=1;s<=sz;s++) if ((s&1)==((s>>1)&1)){
		for (ss=s;ss;ss=(ss-1)&s) if ((ss&1)==((ss>>1)&1)){
			u=ss^s; w=1;
			for (i=0;i<n;i++) if ((s>>i)&1){
				if ((u>>i)&1) w=1ll*w*(bin[cnt[g[i]&ss]]-1)%mod;
				else w=1ll*w*bin[cnt[g[i]&u]]%mod;
			}
			(dp[s]+=1ll*dp[u]*w%mod)%=mod;
		}
	}
	ans=(bin[m]-dp[sz]+mod)%mod;
	printf("%d\n",ans);
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:25:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m); sz=(1<<n)-1;
                     ^
./Main.cpp:27:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&x,&y); x--; y--;
                      ^

Judge Result