POJ 3620 Avoid The Lakes

dfs，统计最多多少个相邻（有公共边）方块。

# include <cstdio>

# include <cstring>



# define N 100 + 15



int n, m, k;

char lake[N][N];

int ans, cur;



const int dx[] = {0,1,0,-1};

const int dy[] = {1,0,-1,0};



void dfs(int x, int y)

{

    lake[x][y] = 0, ++cur;

    for (int i = 0; i < 4; ++i)

    {

        int nx = x + dx[i];

        int ny = y + dy[i];

        if (1<=nx&&nx<=n && 1<=ny&&ny<=m && lake[nx][ny])

        {

            dfs(nx, ny);

        }

    }

}



void init(void)

{

    for (int i = 1; i <= n; ++i)

    {

        memset(lake[i]+1, 0, sizeof(lake[0][0])*m);

    }

    int r, c;

    for (int i = 1; i <= k; ++i)

    {

        scanf("%d%d", &r, &c);

        lake[r][c] = 1;

    }

}



void solve(void)

{

    ans = 0;



    for (int i = 1; i <= n; ++i)

    for (int j = 1; j <= m; ++j)

    {

        cur = 0;

        if (lake[i][j]) dfs(i, j);

        if (cur > ans) ans = cur;

    }



    printf("%d\n", ans);

}



int main()

{

    while (~scanf("%d%d%d", &n, &m, &k))

    {

        init();

        solve();

    }



    return 0;

}