题目
题解
要注意，0是已覆盖，1是未覆盖

#include<cstdio>
#include<cstring>
using namespace std;
int n,m,i,j,k,x;
long long f[2][1<<12];
int main(){
    while (1){
        scanf("%d%d",&n,&m);
        if (!n && !m) return 0;
        memset(f[0],0,sizeof(f[0]));x=0;
        f[0][0]=1;
        for (i=0;i<n;i++)
            for (j=0;j<m;j++,x^=1){
                memset(f[x^1],0,sizeof(f[x^1]));
                if (j)
                    for (k=1;k<1<<m-1;k+=2) f[x^1][k-1<<1]+=f[x][k];
                for (k=0;k<1<<m-1;k++) f[x^1][k<<1^1]+=f[x][k],f[x^1][k<<1]+=f[x][k^1<<m-1];
            }
        printf("%lld\n",f[x][0]);
    }
}