示例1：
在如下矩阵中：
4 4
0 -2 -7 0
9 2 -6 2
-4 1 -4 1
-1 8 0 -2
拥有最大和的子矩阵为：
9 2
-4 1
-1 8
其和为15
示例2：
3 3
-2 10 20
-1 100 -2
0 -2 -3
最大子矩阵和为128
示例3：
4 4
0 -2 -9 -9
-9 11 5 7
-4 -3 -7 -6
-1 7 7 5
最大子矩阵和为26
求解最大子矩阵和的程序
#include <iostream>
using namespace std;
const int SIZE = 100;
int matrix[SIZE + 1][SIZE + 1];
int rowsum[SIZE + 1][SIZE + 1]; /* rowsum[i][j]记录第i行前j个数的和 */
int m, n, i, j, first, last, area, ans;
int main()
{
cin >> m >> n;
for ( i = 1; i <= m; i++ )
for ( j = 1; j <= n; j++ )
cin >> matrix[i][j];
ans = matrix ①;
for ( i = 1; i <= m; i++ )
②;
for ( i = 1; i <= m; i++ )
for ( j = 1; j <= n; j++ )
rowsum[i][j] = ③;
for ( first = 1; first <= n; first++ )
for ( last = first; last <= n; last++ )
{
④;
for ( i = 1; i <= m; i++ )
{
area += ⑤;
if ( area > ans )
ans = area;
if ( area < 0 )
area = 0;
}
}
cout << ans << endl;
return(0);
}