BZOJ 4057: [Cerc2012]Kingdoms

状压DP

#include<cstdio>
#include<cstring>
using namespace std;
int F[1200005],A[25][25],stack[25];
int main(){
	int T;
	scanf("%d",&T);
	while (T--){
		int n;
		scanf("%d",&n);
		for (int i=0; i<n; i++)
			for (int j=0; j<n; j++)
				scanf("%d",&A[i][j]);
		for (int i=0; i<(1<<n); i++) F[i]=0;
		F[(1<<n)-1]=1;
		for (int now=(1<<n)-1; now; now--)
			if (F[now]){
				int top=0;
				for (int i=0; i<n; i++) if (now&(1<<i)) stack[++top]=i;
				for (int i=1; i<=top; i++){
					int Sum=0;
					for (int j=1; j<=top; j++) Sum+=A[stack[j]][stack[i]];
					if (Sum<0) F[now-(1<<stack[i])]=1;
				}
			}
		int f=0;
		for (int i=0; i<n; i++)
			if (F[1<<i]) {
				f++;
				printf("%d ",i+1);
			}
		if (!f) printf("%d",f);
		printf("\n");
	}
	return 0;
}