（DP）To The Max --HDU -- 1081

链接：

http://acm.hdu.edu.cn/showproblem.php?pid=1081

代码：

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define max2(a,b) (a>b?a:b)

#define N 110
#define INF 0xfffffff

int a[N][N], b[N][N][N];

int main()
{
    int n;
    while(scanf("%d", &n)!=EOF)
    {
        int i, j, k, x, max1;

        memset(a, 0, sizeof(a));
        memset(b, 0, sizeof(b));

        for(i=1; i<=n; i++)
        for(j=1; j<=n; j++)
            scanf("%d", &a[i][j]);

        max1=-INF;
        for(i=1; i<=n; i++)
        for(j=1; j<=n; j++)
        for(x=0, k=j; k>0; k--)
        {
            x += a[i][k];

            b[i][j][k] = max2(b[i][j][k], b[i-1][j][k]) + x;

            if(b[i][j][k]>max1)
                max1 = b[i][j][k];
        }

        printf("%d\n", max1);
    }
    return 0;
}