1051 最大子矩阵和

 1 # include <cstdio>
 2 # include <cstring>
 3 # include <cstdlib>
 4 # include <iostream>
 5 # include <vector>
 6 # include <queue>
 7 # include <stack>
 8 # include <map>
 9 # include <bitset>
10 # include <sstream>
11 # include <set>
12 # include <cmath>
13 # include <algorithm>
14 # pragma  comment(linker,"/STACK:102400000,102400000")
15 using namespace std;
16 # define LL          long long
17 # define pr          pair
18 # define mkp         make_pair
19 # define lowbit(x)   ((x)&(-x))
20 # define PI          acos(-1.0)
21 # define INF         0x3f3f3f3f3f3f3f3f
22 # define eps         1e-8
23 # define MOD         1000000007
24 
25 inline int scan() {
26     int x=0,f=1; char ch=getchar();
27     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘) f=-1; ch=getchar();}
28     while(ch>=‘0‘&&ch<=‘9‘){x=x*10+ch-‘0‘; ch=getchar();}
29     return x*f;
30 }
31 inline void Out(int a) {
32     if(a<0) {putchar(‘-‘); a=-a;}
33     if(a>=10) Out(a/10);
34     putchar(a%10+‘0‘);
35 }
36 # define N 505
37 /**************************/
38 LL sum[N][N];
39 
40 int main()
41 {
42     int n ,m;
43     scanf("%d%d",&m,&n);
44     for (int i=1;i<=n;i++)
45     {
46         for (int j=1;j<=m;j++)
47         {
48             int x = scan();
49             sum[i][j]=sum[i][j-1]+x;
50         }
51     }
52     LL ans=0;
53     for (int i=1;i<=m;i++)
54         for (int j=i;j<=m;j++)
55         {
56             LL tp=0;
57             for (int k=1;k<=n;k++)
58             {
59                 tp = max(sum[k][j]-sum[k][i-1]+tp,0LL);
60                 ans = max(tp,ans);
61             }
62         }
63     printf("%lld\n",ans);
64     return 0;
65 }