C++

$\color{gold}{— > 蓝桥杯辅导课题解}$

思路：

DFS

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 25;

int n, m;
char g[N][N];
bool st[N][N];

int dx[] = {-1, 0, 1, 0}, dy[] = {0, 1, 0, -1}; // 偏移量

int dfs(int x, int y) {
    int cnt = 1;
    st[x][y] = true;

    for (int i = 0; i < 4; i ++) { // 枚举上下左右四个方向
        int a = x + dx[i], b = y + dy[i];
        if (a < 0 || a >= n || b < 0 || b >= m) continue; // 越界
        if (g[a][b] != '.') continue; // 不是黑色
        if (st[a][b]) continue; // 已经被搜过

        cnt += dfs(a, b);
    }
    return cnt;
}

int main() {
    while (cin >> m >> n, n || m) {
        for (int i = 0; i < n; i ++) cin >> g[i];

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

        memset(st, 0, sizeof st);            
        cout << dfs(x, y) << endl;            
    }

    return 0;
}