uva 260 - Il Gioco dell'X

题解：

　　一定有人获胜，非黑即白；获胜条件为：black是由 上走到下，white是由 左走到右；

 #include <cstdio>
 using namespace std;
 int N;
 char board[][];
 const int direction[][] = {{-,-},{-,},{,-},{,},{,},{,}};
 void DFS(int i, int j, char c,int &win)
 {
     board[i][j] = '.';
     if (c == 'b' && i == N-) win = ;
     if (c == 'w' && j == N-) win = ;
     for (int x=; x<; ++x){
         int i_next = i+direction[x][];
         int j_next = j+direction[x][];
         if (i_next< || i_next>=N || j_next< || j_next>=N) continue;
         if (board[i_next][j_next] == c)
             DFS(i_next, j_next, c, win);
     }
 }
 int main()
 {
     //reopen("input.txt","rt",stdin);
     int Case = ;
     while (scanf("%d",&N)){
         if (!N) break;
         for (int i=; i<N; ++i)
             scanf("%s",board[i]);
         int win = ; // win=1:Black  win=2:White
         for (int i=; i<N; ++i)
             if (board[i][] == 'w')
                 DFS(i, , 'w', win);
         for (int j=; j<N; ++j)
             if (board[][j] == 'b')
                 DFS(, j, 'b', win);
         if (win == ) printf("%d B\n",Case++);
         else printf("%d W\n",Case++);
     }
     return ;
 }

题解：

　　必有一胜，所以只判断black胜不胜就够了。black胜利的条件是能从第一行走到最后一行，white的胜利条件是能出第一列走到最后一列；

 #include <iostream>
 using namespace std;

 const int maxn =  + ;

 char board[maxn][maxn];

 void wb(int x, int y, int n, char co)
 {
     if(x>= && x<n && y>= && y<n)
         if(board[x][y] == co)
         {
             board[x][y] = '';
             wb(x-, y-, n, co);
             wb(x, y-, n, co);
             wb(x+, y, n, co);
             wb(x-, y, n, co);
             wb(x, y+, n, co);
             wb(x+, y+, n, co);
         }
 }

 int main()
 {
     int n, i, j, ans = ;
     while(cin>>n && n)
     {
         for(i = ; i < n; i++)
             for(j = ; j < n; j++)
                 cin >> board[i][j];

         bool flag = false;
         //black: first row
         for(j = ; j < n; j++)
             if(board[][j] == 'b')
                 wb(, j, n, 'b');
         for(j = ; j < n; j++)
             if(board[n-][j] == '')
             {
                 cout << ++ans << " B" << endl;
                 flag = true;
                 break;
             }

         if(flag)
             continue;
         else cout << ++ans << " W" << endl;
     }
     return ;
 }