BFS Algorithm
#include <iostream>
#include <queue>
using namespace std;
using P = pair<int, int>;
static constexpr int dirs[][2] {{0, -1}, {-1, -1}, {-1, 0}, {-1, 1},
{0, 1}, {1, 1}, {1, 0}, {1, -1}};
const int N = 110;
char g[N][N];
int n, m, sx, sy;
int bfs() {
queue<P> q;
q.emplace(sx, sy);
g[sy][sx] = '*'; // mark as seen
int steps = 0;
while (not q.empty()) {
size_t sz = q.size();
while (sz--) {
const auto [x, y] = q.front(); q.pop();
for (const auto& d : dirs) {
int nx = x + d[0], ny = y + d[1];
if (nx < 0 || ny < 0 || nx == n || ny == m || g[ny][nx] == '*')
continue;
q.emplace(nx, ny);
g[ny][nx] = '*'; // mark as seen
}
}
++steps;
}
return steps - 1;
}
int main() {
cin >> n >> m >> sx >> sy;
for (int y = 0; y < m; ++y) cin >> g[y];
sx -= 1, sy = m - sy; // 坐标偏移
cout << bfs() << endl;
return 0;
}