上代码：

#include<bits/stdc++.h>
using namespace std;
struct asdf{
	int x,y,ex;
};
int n;
int a,b,x,y;
bool d[105][105];
int step[105][105];
int vis[105][105];
int ans = 1e18;
int dx[] = { 0,-1, 0, 1};
int dy[] = {-1, 0, 1, 0};
void bfs(){
	memset(step,0x3f,sizeof(step));
	queue <asdf> q;
	q.push({a,b,0});
	step[a][b] = 0;
	while(!q.empty()){
		asdf tmp = q.front();
		q.pop();
		if(tmp.x == x && tmp.y == y){
			cout << step[tmp.x][tmp.y];
 			return;
		}
		for(int i = 0;i < 4;i++){
			int nx = tmp.x + dx[i];
			int ny = tmp.y + dy[i];
			if(nx < 1 || ny < 1 || nx > n || ny > n || vis[nx][ny] >= 4 || !d[nx][ny]) continue;
			vis[nx][ny]++;
			q.push({nx,ny,i % 2 + 1});
			if(tmp.ex == 1 && i % 2 == 1) step[nx][ny] = min(step[nx][ny],step[tmp.x][tmp.y] + 1);
			else if(tmp.ex == 2 && i % 2 == 0) step[nx][ny] = min(step[nx][ny],step[tmp.x][tmp.y] + 1);
			else step[nx][ny] = min(step[nx][ny],step[tmp.x][tmp.y]);
		}
	}
	cout << -1;
}
int main(){
	cin >> n;
	for(int i = 1;i <= n;i++){
		for(int j = 1;j <= n;j++){
			char c;
			cin >> c;
			if(c == 'x') d[i][j] = 0;
			else if(c == '.') d[i][j] = 1;
			else if(c == 'A') a = i,b = j,d[i][j] = 1;
			else if(c == 'B') x = i,y = j,d[i][j] = 1;
		}
	}
	bfs();
	return 0;
}