全RE！求调

样例能过，but一交全RE（QWQ）~

#include<bits/stdc++.h>
using namespace std;

int dx[4] = {0, 0, -1, 1};
int dy[4] = {-1, 1, 0, 0};
int n, m, sx, sy, ex, ey;
bool vis[1005][1005], mp[1005][1005];

struct node
{
    int x, y, step;
}now, p, pp;

int bfs(int x, int y)
{
    queue<node> que;
    node now = {x, y, -1};
    vis[x][y] = 1;
    que.push(now);
    while(!que.empty())
    {
        p = que.front();
        que.pop();
        for(int i = 0; i < 4; i++)
        {
            int xx = p.x + dx[i];
            int yy = p.y + dy[i];
            while(xx >= 1 && xx <= n && yy >= 1 && yy <= n && !mp[xx][yy])
            {
                pp.x = xx;
        pp.y = yy;
        pp.step = p.step + 1;
                que.push(pp);
                mp[xx][yy] = 1;
                if(pp.x == ex && pp.y == ey)
                {
                    cout << pp.step;
                    return 0;
                }
                xx = xx + dx[i];
                yy = yy + dy[i];
            }
        }   
    }
}

int main()
{
    cin >> n;
    for(int i = 1; i <= n; i++)
    {
        for(int j = 1; j <= n; j++)
        {
            char v;
            cin >> v;
            if(v == '.')
            {
                mp[i][j] = 0;
            }
            else if(v == 'x')
            {
                mp[i][j] = 1;
            }
            else if(v == 'A')
            {
                mp[i][j] = 0;
                sx = i;
                sy = i;
            }
            else if(v == 'B')
            {
                mp[i][j] = 0;
                ex = i;
              ey = i;
            }
        }
    }
    bfs(sx, sy);
    if(pp.step == 0)
    {
        cout << "-1"; 
    } 

    return 0;
}

求调