130. 被围绕的区域

class Solution {
public:
    int dir[4][2]={1,0,0,1,-1,0,0,-1};
    void bfs(vector>& board,vector >&flag,int x,int y){
        queue >q;
        q.push({x,y});
        flag[x][y]=true;
        while(!q.empty()){
            pairp=q.front();
            q.pop();
            int nx=p.first;
            int ny=p.second;
            board[nx][ny]='A';
            for(int i=0;i<4;i++){
                int xx=nx+dir[i][0];
                int yy=ny+dir[i][1];
                if(xx<0||yy<0||xx>=board.size()||yy>=board[0].size()){
                    continue;
                }
                if(board[xx][yy]=='O'&&flag[xx][yy]==false){
                    q.push({xx,yy});
                    flag[xx][yy]=true;
                }
            }
        }
    }
    void solve(vector>& board) {
        int n=board.size();
        int m=board[0].size();
        vector >flag=vector >(n,vector(m,false));
        for(int i=0;i