Submission #1362637

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Source Code Expand

#include<iostream>
#include<cmath>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int n,b[20][20],m,A[20],B[20][20],d[20],two[110000],ans;
const int mo=1e9+7;
void get(int k,int now,int way){
//	cout<<"fa "<<k<<" "<<now<<" "<<way<<endl;
	if (k==2){
	//	for (int i=1;i<=n;i++) cout<<A[i]<<" "; cout<<endl;
	//	for (int i=0;i<=n;i++) cout<<B[1][i]<<" "; cout<<endl;
	//	for (int i=0;i<=n;i++) cout<<B[2][i]<<" "; cout<<endl;
		int rem=d[1]+d[2],tot=1; if (b[1][2]) rem--;
		for (int w=0;w<=now;w++){
			rem-=B[1][w]+B[2][w];
			ans=(ans+((1ll*way*tot%mo)<<rem))%mo;
		//	cout<<"update "<<way<<" "<<tot<<" "<<rem1<<" "<<rem2<<endl;
			if (B[1][w]==0||B[2][w]==0) break;
			tot=1ll*tot*((1<<B[1][w]+B[2][w])-(1<<B[1][w])-(1<<B[2][w])+1)%mo;
		}
		return;
	}
	int rem=d[k]; int tot=1;
	for (int w=0;w<=now;w++){
		for (int i=1;i<k;i++) if (b[i][k]) B[i][w]++; 
		rem-=B[k][w];
		get(k-1,max(w+1,now),((1ll*way*tot%mo)<<rem)%mo);
		for (int i=1;i<k;i++) if (b[i][k]) B[i][w]--;
	//	cout<<k<<" "<<w<<" "<<B[k][w]<<endl;
		if (B[k][w]==0) break;
		tot=1ll*tot*(two[B[k][w]]-1)%mo;
	}
}
int main(){
//	freopen("data.in","r",stdin);
	scanf("%d%d",&n,&m); int prem=m; two[0]=1;
	for (int i=1;i<=m;i++) two[i]=two[i-1]*2%mo;
	if (n==2){
		printf("%d\n",m); return 0;
	}
	for (;m;m--){
		int k1,k2; scanf("%d%d",&k1,&k2); b[k1][k2]=1; d[k1]++;
	}
	get(n,0,1); //cout<<ans<<" "<<two[prem]<<endl;
	ans=(two[prem]-ans+mo)%mo;
	cout<<ans<<endl;
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:38:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m); int prem=m; two[0]=1;
                     ^
./Main.cpp:44:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   int k1,k2; scanf("%d%d",&k1,&k2); b[k1][k2]=1; d[k1]++;
                                   ^

Judge Result