51Nod 1158 全是1的最大子矩阵

 1 #include <cstdio>
 2 #include <cctype>
 3 #include <iostream>
 4 
 5 typedef long long LL;
 6 
 7 const int INF=1000000;
 8 const int MAXN=510;
 9 
10 int n,m;
11 
12 int a[MAXN][MAXN];
13 
14 LL ans;
15 
16 inline void read(int&x) {
17     int f=1;register char c=getchar();
18     for(x=0;!isdigit(c);c==‘-‘&&(f=-1),c=getchar());
19     for(;isdigit(c);x=x*10+c-48,c=getchar());
20     x=x*f;
21 }
22 
23 
24 int hh() {
25     read(n);read(m);
26     for(int i=1;i<=n;++i) 
27       for(int j=1;j<=m;++j) {
28           read(a[i][j]);
29           if(!a[i][j]) a[i][j]=-INF;
30           a[i][j]+=a[i-1][j];
31       }
32     for(int i=0;i<=n;++i)
33       for(int j=i+1;j<=n;++j) {
34           LL tot=0;
35           for(int k=1;k<=m;++k) {
36               if(tot<0) tot=a[j][k]-a[i][k];
37               else tot+=a[j][k]-a[i][k];
38               ans=tot>ans?tot:ans;
39         }
40       }
41     std::cout<<ans;
42     return 0;
43 }
44 
45 int sb=hh();
46 int main(int argc,char**argv) {;}