ZOJ 1074 To the Max

最大矩阵和问题，简单DP

#include  < iostream >
#include  < limits >
using   namespace  std;

const   int  MAXSIZE  =   100 ;
int  a[MAXSIZE][MAXSIZE],b[MAXSIZE],n;

int  maxSubArray()
{ // 计算最大子序列和
     int  curSum = 0 ,sum = numeric_limits < int > ::min();
     for ( int  i = 0 ;i < n;i ++ )
    {
         if (curSum > 0 )
            curSum += b[i];
         else  
            curSum = b[i];
         if (curSum > sum)
            sum = curSum;
    }
     return  sum;  
}
int  maxSubMatrix()
{ // 计算最大子矩阵和
     int  i,j,k,curSum = 0 ,sum = numeric_limits < int > ::min();
     for (i = 0 ;i < n;i ++ )
    {
         for (k = 0 ;k < n;k ++ ) // 初始化b[]
        {
            b[k] = 0 ;
        }
         for (j = i;j < n;j ++ ) // 把第i行到第j行相加,对每一次相加求出最大值
        {
             for (k = 0 ;k < n;k ++ )
            {
                b[k] += a[j][k];
            }
            curSum = maxSubArray();  
             if (curSum > sum)
            {
                sum = curSum;
            }
        }
    }
     return  sum;
}

int  main( void )
{
    cin >> n;
     int  i,j;
     // 输入矩阵
     for  (i = 0 ;i < n; ++ i)
    {
         for (j = 0 ;j < n; ++ j)
        {
            cin >> a[i][j];
        }
    }
    cout << maxSubMatrix() << endl;
     return   0 ;
}