【IDA*+位运算】PKU-1084-Square Destroyer

#include<iostream>
using namespace std;
int n,sqr,maxsqr,maxstep;
__int64 square[20];
__int64 set(int x){return (__int64)1<<(x-1);}
void getsquare()
{
int b,i,j,k,l;
__int64 p[7][7];
for(i=1;i<=n;i++)
for(j=1;j<=n;j++)
{
square[sqr]=set((2*n+1)*(i-1)+j);
square[sqr]+=set((2*n+1)*i+j);
square[sqr]+=set((2*n+1)*(i-1)+n+j);
square[sqr]+=set((2*n+1)*(i-1)+n+j+1);
p[i][j]=square[sqr++];
}
for(b=2;b<=n;b++)
for(i=1;i+b-1<=n;i++)
for(j=1;j+b-1<=n;j++)
{
square[sqr]=0;
for(k=0;k<b;k++)
for(l=0;l<b;l++)
square[sqr]^=p[i+k][j+l];
sqr++;
}
}
bool dfs(__int64 state,int step)
{
int i,needstep=0;
__int64 ch,nows=state,useful=0;
for(i=0;i<sqr;i++)
if((nows&square[i])==square[i])
{
needstep++;
nows^=square[i];
if(useful==0)useful=square[i];
}
if(needstep==0)return true;
if(needstep+step>maxstep)return false;
for(i=1;i<=maxsqr;i++)
{
ch=set(i);
if(ch&useful)
if(dfs(state^ch,step+1))return true;
}
return false;
}
int main()
{
//freopen("a.txt","r",stdin);
int t,i,k,x;
__int64 nows;
scanf("%d",&t);
while(t--)
{
scanf("%d%d",&n,&k);
maxsqr=2*n*(n+1);
sqr=0;
getsquare();
nows=((__int64)1<<maxsqr)-1;
for(i=0;i<k;i++)
{
scanf("%d",&x);
nows^=set(x);
}
for(maxstep=0;!dfs(nows,0);maxstep++);
printf("%d\n",maxstep);
}
return 0;
}