hdu 4920 Matrix multiplication

呵呵呵，一开始傻啦吧唧想0,1,2三个数怎么bitset？！？！！

IQ--

开2个bitset

然后模拟矩阵乘法

#include<cstdio>
#include<algorithm>
#include<bitset>
#define N 1005
using namespace std;
inline int ra()
{
    int x=0,f=1; char ch=getchar();
    while (ch<'0' || ch>'9') {if (ch=='-') f=-1; ch=getchar();}
    while (ch>='0' && ch<='9') {x=x*10+ch-'0'; ch=getchar();}
    return x*f;
}
int n;
bitset<N> a1[N],a2[N],b1[N],b2[N];
int main()
{
    while (~scanf("%d",&n))
    {
        for (int i=1; i<=n; i++)
        {
            a1[i].reset(); a2[i].reset();
            b1[i].reset(); b2[i].reset();
        }
        for (int i=1; i<=n; i++)
            for (int j=1; j<=n; j++)
            {
                int x=ra()%3;
                if (x==1) a1[i][j-1]=1;
                if (x==2) a2[i][j-1]=1;
            }
        for (int i=1; i<=n; i++)
            for (int j=1; j<=n; j++)
            {
                int x=ra()%3;
                if (x==1) b1[j][i-1]=1;
                if (x==2) b2[j][i-1]=1;
            }
        for (int i=1; i<=n; i++)
            for (int j=1; j<=n; j++)
            {
                int a=(a1[i]&b1[j]).count()+4*(a2[i]&b2[j]).count();
                int b=(a1[i]&b2[j]).count()+(a2[i]&b1[j]).count();
                if (j==n) printf("%d
",(a+2*b)%3);
                else printf("%d ",(a+b*2)%3);
            }
        
    }
}