【模板】51nod 1051 最大子矩阵和

 1 #include<cstdio> 
 2 #include<cstring>
 3 #include<algorithm>
 4 #define LL long long
 5 #define N 1000
 6 #define rg register
 7 using namespace std;
 8 int n,m,x;
 9 LL ans,sum[N][N];
10 inline int read(){
11     int k=0,f=1; char c=getchar();
12     while(c<‘0‘||c>‘9‘)c==‘-‘&&(f=-1),c=getchar();
13     while(‘0‘<=c&&c<=‘9‘)k=k*10+c-‘0‘,c=getchar();
14     return k*f;
15 } 
16 int main(){
17     m=read(); n=read();
18     for(rg int i=1;i<=n;i++)
19         for(rg int j=1;j<=m;j++) x=read(),sum[i][j]=sum[i][j-1]+x;
20     for(rg int i=1;i<=m;i++)
21         for(rg int j=i;j<=m;j++){
22             LL tmp=0;
23             for(rg int k=1;k<=n;k++){
24                 tmp+=sum[k][j]-sum[k][i-1];
25                 if(tmp<0) tmp=0;
26                 else ans=max(ans,tmp); 
27             }
28         }
29     printf("%lld\n",ans);
30     return 0;
31 }