hdu 1078:fatmouse and cheese

#include <stdlib.h>
#include <string.h>
#define Max(x,y) (x)>(y)?(x):(y)
int map[100][100],N,k;
int max[100][100];
int iPlus[4] = {-1,0,0,1};
int jPlus[4] = {0,-1,1,0};
typedef struct {
int x,y;
}Node;
int dfs(int x,int y)
{
    int i,j,temp,m;
    int next_x,next_y;
    if ( max[x][y] != -1)
        return max[x][y];
    m = 0;
    for ( i = 0; i < 4; i++)
    {
        for ( j = 1; j <=k ; j++)
        {
            next_x = x + iPlus[i]*j;
            next_y = y + jPlus[i]*j;
            if ( next_x>=0 && next_x < N && next_y>=0 && next_y < N && map[next_x][next_y] > map[x][y])
            {
                temp = dfs(next_x,next_y);
                m = Max(temp,m);
            }
        }
    }
    max[x][y] = m + map[x][y];
    return max[x][y];
}
int main()
{
    int i,j;
    int m;
    while ( scanf("%d%d",&N,&k), N!=-1 && k!=-1)
    {
        for ( i = 0; i < N; i++)
            for ( j = 0; j < N; j++)
                scanf("%d",&map[i][j]);
        memset(max,-1,sizeof(max));
        m = dfs(0,0);
        printf("%dn",m);
    }
    return 0;
}