dfs 深搜

#include <iostream>

using namespace std;

const int N = 30;

int n, m, cnt;
string g[N];
int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};

void dfs(int x, int y)
{
    g[x][y] = '#';
    cnt ++;

    for(int i = 0 ; i < 4; i ++)
    {
        int tx = x + dx[i], ty = y + dy[i];

        if(tx < m && tx >= 0 && ty < n && ty >= 0 && g[tx][ty] == '.')
            dfs(tx, ty);

    }
    return;
}

int main()
{
    while(scanf("%d%d", &n, &m) != EOF && n != 0 && m != 0)
    {
        cnt = 0;
        int x, y;

        for(int i = 0; i < m; i ++)
            cin >> g[i];

        for(int i = 0; i < m; i ++)
            for(int j = 0; j < n; j ++)
            {
                if(g[i][j] == '@')
                    x = i, y = j;
            }
            dfs(x, y);

        cout << cnt << endl;

    }
}

bfs 广搜

#include <iostream>

using namespace std;

struct stu
{
    int x;
    int y;
}que[2510]; 
int main()
{
    int n, m;
    int tx[] = {0, -1, 0, 1}, ty[] = {1, 0, -1, 0};
    while( scanf("%d%d", &n, &m) != EOF && n != 0 && m != 0)
    {

        int p, q, book[25][100] = {0};
        char a[25][100];
        for(int i = 0; i < m; i ++)
            for(int j = 0; j < n; j ++)
            {
                cin >> a[i][j];
                if(a[i][j] == '@')
                    p = i, q = j;
            }
        int x, y, head = 0, tail = 1;
        que[0].x = p, que[0].y = q;
        while(head < tail)
        {
            for(int i =0; i < 4; i ++)
            {
                x = que[head].x + tx[i];
                y = que[head].y + ty[i];
                if(x < 0 || x >= m || y < 0 || y >= n)
                    continue;
                if(a[x][y] == '.' && book[x][y] == 0)
                {
                    book[x][y] = 1;
                    que[tail].x = x;
                    que[tail].y = y;
                    tail ++;
                }           
            }
            head ++;
        }
        printf("%d\n", tail);   
    }
}