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;
}