这一题是一道经典的BFS,由于这一题的坐标是反着的（1， 1）是左下角。所以搜索的坐标给改变一下。下面附上AC代码。

#include <bits/stdc++.h>
using namespace std;
const int N = 205;
char a[N][N];
int vis[N][N];
int n, m, sx, sy, res;

int dx[] = {0, 0, 1, -1, 1, -1, 1, -1};

int dy[] = {1, -1, 0, 0, 1, 1, -1, -1};

struct node {
	int x, y, t;
};

queue<node> q;
void bfs() {
	q.push({sx, sy, 0});
	while (!q.empty()) {
		node t = q.front();
		q.pop();
		res = t.t;
		for (int i = 0; i < 8; i++) {
			int nx = t.x + dx[i];
			int ny = t.y + dy[i];
			if (nx < 1 || nx > n || ny < 1 || ny > m)
				continue;
			if (vis[nx][ny])
				continue;
			if (a[nx][ny] == '*')
				continue;
			vis[nx][ny] = 1;
			q.push({nx, ny, t.t + 1});
		}
	}
}

int main() {
	ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
	cin >> m >> n >> sy >> sx;
	sx = n - sx + 1;
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			cin >> a[i][j];
		}
	}
	vis[sx][sy] = 1;
	bfs();
	cout << res << endl;
	return 0;
}
/*
4 3 2 1
....
..*.
.**.


*/