bzoj1923: [Sdoi2010]外星千足虫

传送门：http://www.lydsy.com:808/JudgeOnline/problem.php?id=1923

裸裸的高斯消元，bitset大法好...

#include<bitset>
#include<cstdio>
#include<cstring>
#include<algorithm>
const int maxn=1010,maxm=2010;
using namespace std;
bitset<maxn> a[maxm];
int n,m,ans;char s[maxn];

void gauss(){
	for (int i=1;i<=n;i++){
		int j=i;
		for (;j<=m&&!a[j][i];j++);
		if (j>m){ans=-1;return;}
		ans=max(ans,j);
		swap(a[i],a[j]);
		for (int j=1;j<=m;j++)
			if (j!=i&&a[j][i])
				a[j]^=a[i];
	}
}

int main(){
	scanf("%d%d",&n,&m);
	for (int i=1,x;i<=m;i++){
		scanf("%s",s+1);
		for (int j=1;j<=n;j++) a[i][j]=s[j]-'0';
		scanf("%d",&x),a[i][n+1]=x;
	}
	gauss();
	if (ans==-1){puts("Cannot Determine");return 0;}
	printf("%d
",ans);
	for (int i=1;i<=n;i++)
		puts(a[i][n+1]?"?y7M#":"Earth");
	return 0;
}

/*6 7
011010 1
101011 0
110100 1
100101 0
011101 0
101011 1
011110 1
*/