1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<cmath> 5 #include<algorithm> 6 #include<queue> 7 #include<stack> 8 #include<cstdlib> 9 using namespace std;10 const int maxn=0x7fffff;11 inline void read(int &n)12 {13     char c=‘+‘;int x=0;bool flag=0;14     while(c<‘0‘||c>‘9‘){c=getchar();if(c==‘-‘)flag=1;}15     while(c>=‘0‘&&c<=‘9‘)16     x=(x<<1)+(x<<3)+c-48,c=getchar();17     flag==1?n=-x:n=x;18 }19 int n,m; 20 int a[99][501];21 int ans=-maxn;22 int cur[501];23 int pos2(int x)24 {25     return (1<<x);26 }27 int dp(int zt)28 {29     memset(cur,0,sizeof(cur));30     int ou,ji;31     for(int i=1;i<=n;i++)32         if(zt&pos2(i))33             for(int j=1;j<=m;j++)34                 cur[j]+=a[i][j];35     bool flag=1;36     for(int i=1;i<=m;i++)37         if(cur[i]>0)38         {39             flag=0;40             break;41         }42     if(flag)43         return -maxn;44     ou=0;ji=0;45     for(int i=1;i<=m;i++)46     {47         if(i&1)48         {49             int x=cur[i]+ou;50             ji=max(ji,x);51         }52         else53         {54             int x=cur[i]+ji;55             ou=max(ou,x);56         }57     }58     return max(ou,ji);59 }60 void dfs(int pos,int last,int zt)61 {62     if(pos==n+1)63     {64         ans=max(ans,dp(zt));65         return ;66     }67 68         if(last==-1||(pos-last)&1)69             dfs(pos+1,pos,zt|pos2(pos));70     dfs(pos+1,last,zt);71 }72 int main()73 {74     read(n);read(m);75     for(int i=1;i<=n;i++)76         for(int j=1;j<=m;j++)77         {78             read(a[i][j]);79             ans=max(ans,a[i][j]);80         }81     if(ans<0)    82     cout<<ans;83     else84     {85         dfs(1,-1,0);86         printf("%d",ans);87     }88     return 0;89 }