P3164 [CQOI2014]和谐矩阵

Posted 2021-01-25 bztminamoto

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位运算太强啦->题解

//minamoto
#include<bits/stdc++.h>
#define ll long long
#define R register
#define fp(i,a,b) for(R int i=a,I=b+1;i<I;++i)
#define fd(i,a,b) for(R int i=a,I=b-1;i>I;--i)
#define go(u) for(R int i=head[u],v=e[i].v;i;i=e[i].nx,v=e[i].v)
using namespace std;
const int N=45,dx[]={1,0,-1,0,0},dy[]={0,1,0,-1,0};
int n,m,h,a[N],b[N];ll lim,res,las,s;bool f[N][N],ans[N][N];
void dfs(int x){
    if(x>h){
        res=las=0;
        fp(i,1,h)b[i]=a[i];
        for(R int i=(m&1)?h-1:h,k=h;i;--i)b[++k]=a[i];
        fp(i,1,m)res=res<<1|(b[i-1]^b[i]^b[i+1]),las=las<<1|b[i];
        fp(i,2,n)s=res,res=las^res^(res<<1&lim)^(res>>1),las=s;
        if(res)return;
        fp(i,1,m)if(ans[1][i]=b[i])fp(j,0,4)f[1+dx[j]][i+dy[j]]^=1;
        fp(i,2,n)fp(j,1,m)if(f[i-1][j]&1){
            ans[i][j]=1;
            fp(k,0,4)f[i+dx[k]][j+dy[k]]^=1;
        }for(R int i=1;i<=n;++i,puts(""))fp(j,1,m)printf("%d ",ans[i][j]);
        exit(0);
    }a[x]=1,dfs(x+1),a[x]=0,dfs(x+1);
}
int main(){
//  freopen("testdata.in","r",stdin);
    scanf("%d%d",&n,&m),h=(m+1)>>1,lim=(1ll<<m)-1;
    dfs(1);return 0;
}