hdoj1421(bfs)

bfs 练习题，简单bfs

题意：给一块地图，找出油田的块的数量，这里要考虑油田的八个方向，上下左右（左右）上（左右）下，存在则可以并在一起。@是油田，*是土地，m是行，n是列。

 

解题思路：用一个二维数组表示8个方向，然后bfs即可。

#include <iostream>
#include <cstdio>
#include <queue>
#include <cstring>
using namespace std;

const int M = 105;
char map[M][M];int m,n;
int res;
struct Oil
{
    int x,y;
};
queue <Oil> oil;
int dire[8][2] = {{-1,0},{0,1},{1,0},{0,-1},{1,1},{-1,-1},{1,-1},{-1,1}};    //方向
void bfs()
{
    while (!oil.empty())
    {
        Oil oo = oil.front();
        oil.pop();
        int dx = oo.x;
        int dy = oo.y;
        for (int i = 0; i < 8; i++)
        {
            int x = dx+dire[i][0];
            int y = dy+dire[i][1];
            if (x >= 0 && x < m && y < n && y >= 0 && map[x][y] == '@')
            {
                map[x][y] = '*';
                Oil o;
                o.x = x;
                o.y = y;                
                oil.push(o);
            }
        }
    }
}
int main()
{
    while (cin >> m >> n && m)
    {
        res = 0;
        memset(visited,0,sizeof (visited));
        for (int i = 0;i < m;i++)
            for (int j = 0;j < n;j++)
                cin >> map[i][j];
        for (int j = 0; j < m; j++)
        {
            for (int k = 0; k < n; k++)
            {
                if (map[j][k] == '@')
                {
                    map[j][k] = '*';
                    Oil oo;
                    oo.x = j;
                    oo.y = k;
                    oil.push(oo);
                    res++;
                    bfs();                    
                }
            }
        }
        cout << res << endl;
    }
    return 0;
}