hdu 5024 枚举

暴力枚举拐角即可．．

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define MAX 107

using namespace std;

int mp[MAX][MAX];
int n,ans;

struct Change
{
    int x1 , y1 , x2 , y2;
}c[MAX];

void init ( )
{
    c[1].x1 = -1 , c[1].y1 =  0;
    c[1].x2 =  0 , c[1].y2 =  1;
    c[2].x1 = -1 , c[2].y1 =  1;
    c[2].x2 =  1 , c[2].y2 =  1;
    c[3].x1 =  0 , c[3].y1 =  1;
    c[3].x2 =  1 , c[3].y2 =  0;
    c[4].x1 =  1 , c[4].y1 =  1;
    c[4].x2 =  1 , c[4].y2 = -1;
    c[5].x1 =  1 , c[5].y1 =  0;
    c[5].x2 =  0 , c[5].y2 = -1;
    c[6].x1 =  1 , c[6].y1 = -1;
    c[6].x2 = -1 , c[6].y2 = -1;
    c[7].x1 =  0 , c[7].y1 = -1;
    c[7].x2 = -1 , c[7].y2 =  0;
    c[8].x1 = -1 , c[8].y1 = -1;
    c[8].x2 = -1 , c[8].y2 =  1;  
}

void out ( )
{
    for ( int i = 1 ; i <= n ; i++ )
    {
        for ( int j = 1 ; j <= n ; j++ )
            cout << mp[i][j] << " ";
        cout << endl;
    }
}

int main ( )
{
    init ( );
    char ch;
    while ( ~scanf ( "%d" , &n ) , n )
    {
        ans = 0;
        memset ( mp , 0 , sizeof ( mp ) );
        for ( int i = 1 ; i <= n ; i++ )
        {
            getchar();
            for ( int j = 1 ; j <= n ; j++ )
            {
                ch = getchar();
                if ( ch == '.' ) mp[i][j] = 1;
            }
        }
       // out ( );
        for ( int i = 1 ; i <= n ; i++ )
            for ( int j = 1 ; j <= n ; j++ )
                if ( mp[i][j] )
                    for ( int k = 1 ; k <= 8 ; k++ )
                    {

                       // cout << "YES" << endl;
                       /* cout << c[k].x1 << " "
                             << c[k].y1 << " "
                             << c[k].x2 << " "
                             << c[k].y2 << endl;*/
                        int cnt = 1;
                        for ( int t = 1 ;;t++ )
                        {
                            /*cout << i+c[k].x1 *t << " "
                                 << j+c[k].y1 *t << endl;*/
                            if ( !mp[i+c[k].x1*t][j+c[k].y1*t] )
                            {
                                cnt += (t-1);
                                break;
                            }
                        }
                        for ( int t = 1 ;; t++ )
                        {
                          /*  cout << i + c[k].x2*t << " "
                                 << j + c[k].y2*t << endl;*/
                            if ( !mp[i+c[k].x2*t][j+c[k].y2*t] )
                            {
                                cnt += (t-1);
                                break;
                            }
                        }
                       // cout << "Okay" << endl;
                        ans = max ( cnt , ans );
                    }
        printf ( "%d\n" , ans );
    }   
}