Submission #66109829

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;
int read(){int f=0,x=0;char a=getchar();while(!isdigit(a)){if(a=='-')f=1;a=getchar();}while(isdigit(a)){x=x*10+a-'0';a=getchar();}if(f)return -x;return x;}
long long h,w,a[27][27],ans;
bool yw[27][27];
void dfs(int x,int y)
{
    if(x>h)
    {
            long long tmp=0;
        for(int i=1;i<=h;i++)
        {
            for(int j=1;j<=w;j++)
            {
                if(!yw[i][j])tmp^=a[i][j];
            }
        }
        ans=max(ans,tmp);
        return;
    }
    if(y>w)
    {
        dfs(x+1,y-w);
        return;
    }
    if(!yw[x][y]&&!yw[x][y+1]&&y<w)
    {
        yw[x][y]=yw[x][y+1]=1;
        dfs(x,y+2);
        yw[x][y]=yw[x][y+1]=0;
    }
    if(!yw[x][y]&&!yw[x+1][y]&&x<h)
    {
        yw[x][y]=yw[x+1][y]=1;
        dfs(x,y+1);
        yw[x][y]=yw[x+1][y]=0;
    }
    dfs(x,y+1);
}
int main()
{
    //freopen(in.in,r,stdin);
    //freopen(out.out,w,stdout);
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin>>h>>w;
    for(int i=1;i<=h;i++)
    {
        for(int j=1;j<=w;j++)
        {
            cin>>a[i][j];
        }
    }
    dfs(1,1);
    cout<<ans;
    return 0;
}

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