http://poj.org/problem?id=3620

DFS

从任意一个lake出发

重置联通的lake 并且记录 更新ans

1 #include 
     
       2 #include 
      
        3 #include 
       
         4 using namespace std; 5  6  7 int N,M,K; 8 bool pool[107][107]; 9 int d[4][2] = {-1, 0, 0, 1, 1, 0, 0, -1};10 int res = 0;11 int ans = 0;12 bool OK(int x, int y)13 {14     if (x < 0 || x > N || y < 0 || y > M) return false;15     return pool[x][y];16 }17 void dfs(int x, int y)18 {19     res++;20     pool[x][y] = false;21     int nx, ny;22     for (int i = 0; i < 4; i++)23     {24         nx = x+d[i][0];25         ny = y+d[i][1];26         if ( OK(nx, ny) )27         {28             dfs(nx, ny);29         }30     }31 }32 int main()33 {
    35     while (cin >> N >> M >> K)36     {37         memset(pool, 0, sizeof(pool));38         for (int i = 0; i < K; i++)39         {40             int r, c;41             scanf("%d%d", &r, &c);42             pool[r][c] = true;43         }44         res = 0;45         ans = 0;46         for (int i = 1; i <= N; i++)47         for (int j = 1; j <= M; j++)48         {49           if (OK(i, j))50           {51               res = 0;52               dfs(i, j);53           }54           ans = max(ans, res);55         }56         cout << ans << endl;57     }58     return 0;59 }