POJ 3620 Avoid The Lakes

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

#include <iostream>
#include <string.h>
#include <stdio.h>
using namespace std;


int N,M,K;
bool pool[107][107];
int d[4][2] = {-1, 0, 0, 1, 1, 0, 0, -1};
int res = 0;
int ans = 0;
bool OK(int x, int y)
{
    if (x < 0 || x > N || y < 0 || y > M) return false;
    return pool[x][y];
}
void dfs(int x, int y)
{
    res++;
    pool[x][y] = false;
    int nx, ny;
    for (int i = 0; i < 4; i++)
    {
        nx = x+d[i][0];
        ny = y+d[i][1];
        if ( OK(nx, ny) )
        {
            dfs(nx, ny);
        }
    }
}
int main()
{35     while (cin >> N >> M >> K)
    {
        memset(pool, 0, sizeof(pool));
        for (int i = 0; i < K; i++)
        {
            int r, c;
            scanf("%d%d", &r, &c);
            pool[r][c] = true;
        }
        res = 0;
        ans = 0;
        for (int i = 1; i <= N; i++)
        for (int j = 1; j <= M; j++)
        {
          if (OK(i, j))
          {
              res = 0;
              dfs(i, j);
          }
          ans = max(ans, res);
        }
        cout << ans << endl;
    }
    return 0;
}